170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * jquant2.c 370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Copyright (C) 1991-1996, Thomas G. Lane. 570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This file is part of the Independent JPEG Group's software. 670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * For conditions of distribution and use, see the accompanying README file. 770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This file contains 2-pass color quantization (color mapping) routines. 970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * These routines provide selection of a custom color map for an image, 1070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * followed by mapping of the image to that color map, with optional 1170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Floyd-Steinberg dithering. 1270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * It is also possible to use just the second pass to map to an arbitrary 1370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * externally-given color map. 1470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 1570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Note: ordered dithering is not supported, since there isn't any fast 1670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * way to compute intercolor distances; it's unclear that ordered dither's 1770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * fundamental assumptions even hold with an irregularly spaced color map. 1870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 1970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 2070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define JPEG_INTERNALS 2170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#include "jinclude.h" 2270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#include "jpeglib.h" 2370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 2470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#ifdef QUANT_2PASS_SUPPORTED 2570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 2670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 2770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 2870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This module implements the well-known Heckbert paradigm for color 2970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * quantization. Most of the ideas used here can be traced back to 3070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Heckbert's seminal paper 3170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Heckbert, Paul. "Color Image Quantization for Frame Buffer Display", 3270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Proc. SIGGRAPH '82, Computer Graphics v.16 #3 (July 1982), pp 297-304. 3370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 3470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * In the first pass over the image, we accumulate a histogram showing the 3570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * usage count of each possible color. To keep the histogram to a reasonable 3670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * size, we reduce the precision of the input; typical practice is to retain 3770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 5 or 6 bits per color, so that 8 or 4 different input values are counted 3870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * in the same histogram cell. 3970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 4070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Next, the color-selection step begins with a box representing the whole 4170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * color space, and repeatedly splits the "largest" remaining box until we 4270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * have as many boxes as desired colors. Then the mean color in each 4370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * remaining box becomes one of the possible output colors. 4470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 4570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The second pass over the image maps each input pixel to the closest output 4670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * color (optionally after applying a Floyd-Steinberg dithering correction). 4770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This mapping is logically trivial, but making it go fast enough requires 4870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * considerable care. 4970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 5070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Heckbert-style quantizers vary a good deal in their policies for choosing 5170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * the "largest" box and deciding where to cut it. The particular policies 5270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * used here have proved out well in experimental comparisons, but better ones 5370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * may yet be found. 5470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 5570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * In earlier versions of the IJG code, this module quantized in YCbCr color 5670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * space, processing the raw upsampled data without a color conversion step. 5770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This allowed the color conversion math to be done only once per colormap 5870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * entry, not once per pixel. However, that optimization precluded other 5970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * useful optimizations (such as merging color conversion with upsampling) 6070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * and it also interfered with desired capabilities such as quantizing to an 6170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * externally-supplied colormap. We have therefore abandoned that approach. 6270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The present code works in the post-conversion color space, typically RGB. 6370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 6470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * To improve the visual quality of the results, we actually work in scaled 6570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * RGB space, giving G distances more weight than R, and R in turn more than 6670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * B. To do everything in integer math, we must use integer scale factors. 6770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The 2/3/1 scale factors used here correspond loosely to the relative 6870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * weights of the colors in the NTSC grayscale equation. 6970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * If you want to use this code to quantize a non-RGB color space, you'll 7070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * probably need to change these scale factors. 7170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 7270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 7370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define R_SCALE 2 /* scale R distances by this much */ 7470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define G_SCALE 3 /* scale G distances by this much */ 7570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define B_SCALE 1 /* and B by this much */ 7670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 7770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Relabel R/G/B as components 0/1/2, respecting the RGB ordering defined 7870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * in jmorecfg.h. As the code stands, it will do the right thing for R,G,B 7970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * and B,G,R orders. If you define some other weird order in jmorecfg.h, 8070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * you'll get compile errors until you extend this logic. In that case 8170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * you'll probably want to tweak the histogram sizes too. 8270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 8370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 8470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#if RGB_RED == 0 8570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define C0_SCALE R_SCALE 8670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif 8770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#if RGB_BLUE == 0 8870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define C0_SCALE B_SCALE 8970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif 9070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#if RGB_GREEN == 1 9170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define C1_SCALE G_SCALE 9270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif 9370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#if RGB_RED == 2 9470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define C2_SCALE R_SCALE 9570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif 9670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#if RGB_BLUE == 2 9770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define C2_SCALE B_SCALE 9870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif 9970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 10070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 10170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 10270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * First we have the histogram data structure and routines for creating it. 10370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 10470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The number of bits of precision can be adjusted by changing these symbols. 10570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * We recommend keeping 6 bits for G and 5 each for R and B. 10670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * If you have plenty of memory and cycles, 6 bits all around gives marginally 10770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * better results; if you are short of memory, 5 bits all around will save 10870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * some space but degrade the results. 10970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * To maintain a fully accurate histogram, we'd need to allocate a "long" 11070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * (preferably unsigned long) for each cell. In practice this is overkill; 11170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * we can get by with 16 bits per cell. Few of the cell counts will overflow, 11270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * and clamping those that do overflow to the maximum value will give close- 11370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * enough results. This reduces the recommended histogram size from 256Kb 11470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * to 128Kb, which is a useful savings on PC-class machines. 11570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * (In the second pass the histogram space is re-used for pixel mapping data; 11670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * in that capacity, each cell must be able to store zero to the number of 11770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * desired colors. 16 bits/cell is plenty for that too.) 11870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Since the JPEG code is intended to run in small memory model on 80x86 11970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * machines, we can't just allocate the histogram in one chunk. Instead 12070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * of a true 3-D array, we use a row of pointers to 2-D arrays. Each 12170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * pointer corresponds to a C0 value (typically 2^5 = 32 pointers) and 12270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * each 2-D array has 2^6*2^5 = 2048 or 2^6*2^6 = 4096 entries. Note that 12370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * on 80x86 machines, the pointer row is in near memory but the actual 12470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * arrays are in far memory (same arrangement as we use for image arrays). 12570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 12670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 12770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define MAXNUMCOLORS (MAXJSAMPLE+1) /* maximum size of colormap */ 12870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 12970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* These will do the right thing for either R,G,B or B,G,R color order, 13070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * but you may not like the results for other color orders. 13170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 13270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define HIST_C0_BITS 5 /* bits of precision in R/B histogram */ 13370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define HIST_C1_BITS 6 /* bits of precision in G histogram */ 13470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define HIST_C2_BITS 5 /* bits of precision in B/R histogram */ 13570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 13670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Number of elements along histogram axes. */ 13770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define HIST_C0_ELEMS (1<<HIST_C0_BITS) 13870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define HIST_C1_ELEMS (1<<HIST_C1_BITS) 13970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define HIST_C2_ELEMS (1<<HIST_C2_BITS) 14070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 14170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* These are the amounts to shift an input value to get a histogram index. */ 14270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define C0_SHIFT (BITS_IN_JSAMPLE-HIST_C0_BITS) 14370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define C1_SHIFT (BITS_IN_JSAMPLE-HIST_C1_BITS) 14470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define C2_SHIFT (BITS_IN_JSAMPLE-HIST_C2_BITS) 14570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 14670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 14770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef UINT16 histcell; /* histogram cell; prefer an unsigned type */ 14870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 14970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef histcell FAR * histptr; /* for pointers to histogram cells */ 15070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 15170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef histcell hist1d[HIST_C2_ELEMS]; /* typedefs for the array */ 15270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef hist1d FAR * hist2d; /* type for the 2nd-level pointers */ 15370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef hist2d * hist3d; /* type for top-level pointer */ 15470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 15570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 15670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Declarations for Floyd-Steinberg dithering. 15770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 15870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Errors are accumulated into the array fserrors[], at a resolution of 15970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 1/16th of a pixel count. The error at a given pixel is propagated 16070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * to its not-yet-processed neighbors using the standard F-S fractions, 16170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * ... (here) 7/16 16270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 3/16 5/16 1/16 16370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * We work left-to-right on even rows, right-to-left on odd rows. 16470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 16570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * We can get away with a single array (holding one row's worth of errors) 16670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * by using it to store the current row's errors at pixel columns not yet 16770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * processed, but the next row's errors at columns already processed. We 16870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * need only a few extra variables to hold the errors immediately around the 16970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * current column. (If we are lucky, those variables are in registers, but 17070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * even if not, they're probably cheaper to access than array elements are.) 17170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 17270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The fserrors[] array has (#columns + 2) entries; the extra entry at 17370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * each end saves us from special-casing the first and last pixels. 17470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Each entry is three values long, one value for each color component. 17570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 17670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Note: on a wide image, we might not have enough room in a PC's near data 17770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * segment to hold the error array; so it is allocated with alloc_large. 17870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 17970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 18070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#if BITS_IN_JSAMPLE == 8 18170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef INT16 FSERROR; /* 16 bits should be enough */ 18270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef int LOCFSERROR; /* use 'int' for calculation temps */ 18370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#else 18470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef INT32 FSERROR; /* may need more than 16 bits */ 18570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef INT32 LOCFSERROR; /* be sure calculation temps are big enough */ 18670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif 18770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 18870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef FSERROR FAR *FSERRPTR; /* pointer to error array (in FAR storage!) */ 18970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 19070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 19170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Private subobject */ 19270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 19370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef struct { 19470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine struct jpeg_color_quantizer pub; /* public fields */ 19570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 19670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Space for the eventually created colormap is stashed here */ 19770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPARRAY sv_colormap; /* colormap allocated at init time */ 19870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int desired; /* desired # of colors = size of colormap */ 19970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 20070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Variables for accumulating image statistics */ 20170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine hist3d histogram; /* pointer to the histogram */ 20270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 20370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boolean needs_zeroed; /* TRUE if next pass must zero histogram */ 20470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 20570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Variables for Floyd-Steinberg dithering */ 20670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine FSERRPTR fserrors; /* accumulated errors */ 20770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boolean on_odd_row; /* flag to remember which row we are on */ 20870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int * error_limiter; /* table for clamping the applied error */ 20970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} my_cquantizer; 21070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 21170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef my_cquantizer * my_cquantize_ptr; 21270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 21370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 21470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 21570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Prescan some rows of pixels. 21670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * In this module the prescan simply updates the histogram, which has been 21770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * initialized to zeroes by start_pass. 21870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * An output_buf parameter is required by the method signature, but no data 21970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * is actually output (in fact the buffer controller is probably passing a 22070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * NULL pointer). 22170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 22270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 22370a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineMETHODDEF(void) 22470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkineprescan_quantize (j_decompress_ptr cinfo, JSAMPARRAY input_buf, 22570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPARRAY output_buf, int num_rows) 22670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 22770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; 22870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register JSAMPROW ptr; 22970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register histptr histp; 23070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register hist3d histogram = cquantize->histogram; 23170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int row; 23270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JDIMENSION col; 23370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JDIMENSION width = cinfo->output_width; 23470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 23570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (row = 0; row < num_rows; row++) { 23670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ptr = input_buf[row]; 23770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (col = width; col > 0; col--) { 23870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* get pixel value and index into the histogram */ 23970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine histp = & histogram[GETJSAMPLE(ptr[0]) >> C0_SHIFT] 24070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine [GETJSAMPLE(ptr[1]) >> C1_SHIFT] 24170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine [GETJSAMPLE(ptr[2]) >> C2_SHIFT]; 24270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* increment, check for overflow and undo increment if so. */ 24370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (++(*histp) <= 0) 24470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine (*histp)--; 24570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ptr += 3; 24670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 24770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 24870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 24970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 25070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 25170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 25270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Next we have the really interesting routines: selection of a colormap 25370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * given the completed histogram. 25470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * These routines work with a list of "boxes", each representing a rectangular 25570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * subset of the input color space (to histogram precision). 25670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 25770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 25870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef struct { 25970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* The bounds of the box (inclusive); expressed as histogram indexes */ 26070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int c0min, c0max; 26170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int c1min, c1max; 26270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int c2min, c2max; 26370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* The volume (actually 2-norm) of the box */ 26470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine INT32 volume; 26570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* The number of nonzero histogram cells within this box */ 26670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine long colorcount; 26770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} box; 26870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 26970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef box * boxptr; 27070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 27170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 27270a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineLOCAL(boxptr) 27370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinefind_biggest_color_pop (boxptr boxlist, int numboxes) 27470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Find the splittable box with the largest color population */ 27570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Returns NULL if no splittable boxes remain */ 27670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 27770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register boxptr boxp; 27870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register int i; 27970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register long maxc = 0; 28070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxptr which = NULL; 28170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 28270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (i = 0, boxp = boxlist; i < numboxes; i++, boxp++) { 28370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (boxp->colorcount > maxc && boxp->volume > 0) { 28470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine which = boxp; 28570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine maxc = boxp->colorcount; 28670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 28770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 28870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine return which; 28970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 29070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 29170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 29270a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineLOCAL(boxptr) 29370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinefind_biggest_volume (boxptr boxlist, int numboxes) 29470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Find the splittable box with the largest (scaled) volume */ 29570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Returns NULL if no splittable boxes remain */ 29670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 29770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register boxptr boxp; 29870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register int i; 29970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register INT32 maxv = 0; 30070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxptr which = NULL; 30170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 30270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (i = 0, boxp = boxlist; i < numboxes; i++, boxp++) { 30370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (boxp->volume > maxv) { 30470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine which = boxp; 30570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine maxv = boxp->volume; 30670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 30770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 30870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine return which; 30970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 31070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 31170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 31270a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineLOCAL(void) 31370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkineupdate_box (j_decompress_ptr cinfo, boxptr boxp) 31470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Shrink the min/max bounds of a box to enclose only nonzero elements, */ 31570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* and recompute its volume and population */ 31670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 31770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; 31870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine hist3d histogram = cquantize->histogram; 31970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine histptr histp; 32070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int c0,c1,c2; 32170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int c0min,c0max,c1min,c1max,c2min,c2max; 32270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine INT32 dist0,dist1,dist2; 32370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine long ccount; 32470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 32570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c0min = boxp->c0min; c0max = boxp->c0max; 32670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c1min = boxp->c1min; c1max = boxp->c1max; 32770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c2min = boxp->c2min; c2max = boxp->c2max; 32870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 32970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (c0max > c0min) 33070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c0 = c0min; c0 <= c0max; c0++) 33170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c1 = c1min; c1 <= c1max; c1++) { 33270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine histp = & histogram[c0][c1][c2min]; 33370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c2 = c2min; c2 <= c2max; c2++) 33470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (*histp++ != 0) { 33570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxp->c0min = c0min = c0; 33670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine goto have_c0min; 33770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 33870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 33970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine have_c0min: 34070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (c0max > c0min) 34170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c0 = c0max; c0 >= c0min; c0--) 34270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c1 = c1min; c1 <= c1max; c1++) { 34370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine histp = & histogram[c0][c1][c2min]; 34470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c2 = c2min; c2 <= c2max; c2++) 34570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (*histp++ != 0) { 34670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxp->c0max = c0max = c0; 34770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine goto have_c0max; 34870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 34970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 35070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine have_c0max: 35170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (c1max > c1min) 35270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c1 = c1min; c1 <= c1max; c1++) 35370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c0 = c0min; c0 <= c0max; c0++) { 35470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine histp = & histogram[c0][c1][c2min]; 35570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c2 = c2min; c2 <= c2max; c2++) 35670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (*histp++ != 0) { 35770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxp->c1min = c1min = c1; 35870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine goto have_c1min; 35970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 36070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 36170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine have_c1min: 36270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (c1max > c1min) 36370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c1 = c1max; c1 >= c1min; c1--) 36470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c0 = c0min; c0 <= c0max; c0++) { 36570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine histp = & histogram[c0][c1][c2min]; 36670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c2 = c2min; c2 <= c2max; c2++) 36770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (*histp++ != 0) { 36870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxp->c1max = c1max = c1; 36970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine goto have_c1max; 37070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 37170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 37270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine have_c1max: 37370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (c2max > c2min) 37470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c2 = c2min; c2 <= c2max; c2++) 37570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c0 = c0min; c0 <= c0max; c0++) { 37670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine histp = & histogram[c0][c1min][c2]; 37770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c1 = c1min; c1 <= c1max; c1++, histp += HIST_C2_ELEMS) 37870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (*histp != 0) { 37970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxp->c2min = c2min = c2; 38070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine goto have_c2min; 38170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 38270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 38370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine have_c2min: 38470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (c2max > c2min) 38570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c2 = c2max; c2 >= c2min; c2--) 38670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c0 = c0min; c0 <= c0max; c0++) { 38770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine histp = & histogram[c0][c1min][c2]; 38870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c1 = c1min; c1 <= c1max; c1++, histp += HIST_C2_ELEMS) 38970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (*histp != 0) { 39070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxp->c2max = c2max = c2; 39170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine goto have_c2max; 39270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 39370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 39470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine have_c2max: 39570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 39670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Update box volume. 39770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * We use 2-norm rather than real volume here; this biases the method 39870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * against making long narrow boxes, and it has the side benefit that 39970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * a box is splittable iff norm > 0. 40070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Since the differences are expressed in histogram-cell units, 40170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * we have to shift back to JSAMPLE units to get consistent distances; 40270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * after which, we scale according to the selected distance scale factors. 40370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 40470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dist0 = ((c0max - c0min) << C0_SHIFT) * C0_SCALE; 40570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dist1 = ((c1max - c1min) << C1_SHIFT) * C1_SCALE; 40670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dist2 = ((c2max - c2min) << C2_SHIFT) * C2_SCALE; 40770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxp->volume = dist0*dist0 + dist1*dist1 + dist2*dist2; 40870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 40970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Now scan remaining volume of box and compute population */ 41070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ccount = 0; 41170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c0 = c0min; c0 <= c0max; c0++) 41270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c1 = c1min; c1 <= c1max; c1++) { 41370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine histp = & histogram[c0][c1][c2min]; 41470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c2 = c2min; c2 <= c2max; c2++, histp++) 41570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (*histp != 0) { 41670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ccount++; 41770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 41870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 41970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxp->colorcount = ccount; 42070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 42170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 42270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 42370a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineLOCAL(int) 42470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinemedian_cut (j_decompress_ptr cinfo, boxptr boxlist, int numboxes, 42570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int desired_colors) 42670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Repeatedly select and split the largest box until we have enough boxes */ 42770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 42870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int n,lb; 42970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int c0,c1,c2,cmax; 43070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register boxptr b1,b2; 43170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 43270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine while (numboxes < desired_colors) { 43370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Select box to split. 43470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Current algorithm: by population for first half, then by volume. 43570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 43670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (numboxes*2 <= desired_colors) { 43770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine b1 = find_biggest_color_pop(boxlist, numboxes); 43870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else { 43970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine b1 = find_biggest_volume(boxlist, numboxes); 44070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 44170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (b1 == NULL) /* no splittable boxes left! */ 44270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine break; 44370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine b2 = &boxlist[numboxes]; /* where new box will go */ 44470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Copy the color bounds to the new box. */ 44570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine b2->c0max = b1->c0max; b2->c1max = b1->c1max; b2->c2max = b1->c2max; 44670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine b2->c0min = b1->c0min; b2->c1min = b1->c1min; b2->c2min = b1->c2min; 44770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Choose which axis to split the box on. 44870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Current algorithm: longest scaled axis. 44970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * See notes in update_box about scaling distances. 45070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 45170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c0 = ((b1->c0max - b1->c0min) << C0_SHIFT) * C0_SCALE; 45270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c1 = ((b1->c1max - b1->c1min) << C1_SHIFT) * C1_SCALE; 45370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c2 = ((b1->c2max - b1->c2min) << C2_SHIFT) * C2_SCALE; 45470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* We want to break any ties in favor of green, then red, blue last. 45570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This code does the right thing for R,G,B or B,G,R color orders only. 45670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 45770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#if RGB_RED == 0 45870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cmax = c1; n = 1; 45970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (c0 > cmax) { cmax = c0; n = 0; } 46070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (c2 > cmax) { n = 2; } 46170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#else 46270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cmax = c1; n = 1; 46370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (c2 > cmax) { cmax = c2; n = 2; } 46470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (c0 > cmax) { n = 0; } 46570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif 46670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Choose split point along selected axis, and update box bounds. 46770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Current algorithm: split at halfway point. 46870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * (Since the box has been shrunk to minimum volume, 46970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * any split will produce two nonempty subboxes.) 47070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Note that lb value is max for lower box, so must be < old max. 47170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 47270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine switch (n) { 47370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine case 0: 47470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine lb = (b1->c0max + b1->c0min) / 2; 47570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine b1->c0max = lb; 47670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine b2->c0min = lb+1; 47770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine break; 47870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine case 1: 47970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine lb = (b1->c1max + b1->c1min) / 2; 48070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine b1->c1max = lb; 48170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine b2->c1min = lb+1; 48270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine break; 48370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine case 2: 48470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine lb = (b1->c2max + b1->c2min) / 2; 48570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine b1->c2max = lb; 48670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine b2->c2min = lb+1; 48770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine break; 48870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 48970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Update stats for boxes */ 49070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine update_box(cinfo, b1); 49170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine update_box(cinfo, b2); 49270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine numboxes++; 49370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 49470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine return numboxes; 49570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 49670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 49770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 49870a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineLOCAL(void) 49970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinecompute_color (j_decompress_ptr cinfo, boxptr boxp, int icolor) 50070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Compute representative color for a box, put it in colormap[icolor] */ 50170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 50270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Current algorithm: mean weighted by pixels (not colors) */ 50370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Note it is important to get the rounding correct! */ 50470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; 50570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine hist3d histogram = cquantize->histogram; 50670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine histptr histp; 50770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int c0,c1,c2; 50870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int c0min,c0max,c1min,c1max,c2min,c2max; 50970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine long count; 51070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine long total = 0; 51170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine long c0total = 0; 51270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine long c1total = 0; 51370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine long c2total = 0; 51470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 51570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c0min = boxp->c0min; c0max = boxp->c0max; 51670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c1min = boxp->c1min; c1max = boxp->c1max; 51770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c2min = boxp->c2min; c2max = boxp->c2max; 51870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 51970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c0 = c0min; c0 <= c0max; c0++) 52070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c1 = c1min; c1 <= c1max; c1++) { 52170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine histp = & histogram[c0][c1][c2min]; 52270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (c2 = c2min; c2 <= c2max; c2++) { 52370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if ((count = *histp++) != 0) { 52470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine total += count; 52570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c0total += ((c0 << C0_SHIFT) + ((1<<C0_SHIFT)>>1)) * count; 52670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c1total += ((c1 << C1_SHIFT) + ((1<<C1_SHIFT)>>1)) * count; 52770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c2total += ((c2 << C2_SHIFT) + ((1<<C2_SHIFT)>>1)) * count; 52870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 52970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 53070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 53170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 53270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cinfo->colormap[0][icolor] = (JSAMPLE) ((c0total + (total>>1)) / total); 53370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cinfo->colormap[1][icolor] = (JSAMPLE) ((c1total + (total>>1)) / total); 53470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cinfo->colormap[2][icolor] = (JSAMPLE) ((c2total + (total>>1)) / total); 53570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 53670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 53770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 53870a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineLOCAL(void) 53970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkineselect_colors (j_decompress_ptr cinfo, int desired_colors) 54070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Master routine for color selection */ 54170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 54270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxptr boxlist; 54370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int numboxes; 54470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int i; 54570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 54670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Allocate workspace for box list */ 54770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxlist = (boxptr) (*cinfo->mem->alloc_small) 54870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ((j_common_ptr) cinfo, JPOOL_IMAGE, desired_colors * SIZEOF(box)); 54970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Initialize one box containing whole space */ 55070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine numboxes = 1; 55170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxlist[0].c0min = 0; 55270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxlist[0].c0max = MAXJSAMPLE >> C0_SHIFT; 55370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxlist[0].c1min = 0; 55470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxlist[0].c1max = MAXJSAMPLE >> C1_SHIFT; 55570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxlist[0].c2min = 0; 55670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine boxlist[0].c2max = MAXJSAMPLE >> C2_SHIFT; 55770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Shrink it to actually-used volume and set its statistics */ 55870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine update_box(cinfo, & boxlist[0]); 55970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Perform median-cut to produce final box list */ 56070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine numboxes = median_cut(cinfo, boxlist, numboxes, desired_colors); 56170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Compute the representative color for each box, fill colormap */ 56270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (i = 0; i < numboxes; i++) 56370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine compute_color(cinfo, & boxlist[i], i); 56470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cinfo->actual_number_of_colors = numboxes; 56570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine TRACEMS1(cinfo, 1, JTRC_QUANT_SELECTED, numboxes); 56670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 56770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 56870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 56970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 57070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * These routines are concerned with the time-critical task of mapping input 57170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * colors to the nearest color in the selected colormap. 57270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 57370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * We re-use the histogram space as an "inverse color map", essentially a 57470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * cache for the results of nearest-color searches. All colors within a 57570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * histogram cell will be mapped to the same colormap entry, namely the one 57670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * closest to the cell's center. This may not be quite the closest entry to 57770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * the actual input color, but it's almost as good. A zero in the cache 57870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * indicates we haven't found the nearest color for that cell yet; the array 57970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * is cleared to zeroes before starting the mapping pass. When we find the 58070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * nearest color for a cell, its colormap index plus one is recorded in the 58170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * cache for future use. The pass2 scanning routines call fill_inverse_cmap 58270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * when they need to use an unfilled entry in the cache. 58370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 58470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Our method of efficiently finding nearest colors is based on the "locally 58570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * sorted search" idea described by Heckbert and on the incremental distance 58670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * calculation described by Spencer W. Thomas in chapter III.1 of Graphics 58770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Gems II (James Arvo, ed. Academic Press, 1991). Thomas points out that 58870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * the distances from a given colormap entry to each cell of the histogram can 58970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * be computed quickly using an incremental method: the differences between 59070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * distances to adjacent cells themselves differ by a constant. This allows a 59170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * fairly fast implementation of the "brute force" approach of computing the 59270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * distance from every colormap entry to every histogram cell. Unfortunately, 59370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * it needs a work array to hold the best-distance-so-far for each histogram 59470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * cell (because the inner loop has to be over cells, not colormap entries). 59570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The work array elements have to be INT32s, so the work array would need 59670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 256Kb at our recommended precision. This is not feasible in DOS machines. 59770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 59870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * To get around these problems, we apply Thomas' method to compute the 59970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * nearest colors for only the cells within a small subbox of the histogram. 60070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The work array need be only as big as the subbox, so the memory usage 60170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * problem is solved. Furthermore, we need not fill subboxes that are never 60270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * referenced in pass2; many images use only part of the color gamut, so a 60370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * fair amount of work is saved. An additional advantage of this 60470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * approach is that we can apply Heckbert's locality criterion to quickly 60570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * eliminate colormap entries that are far away from the subbox; typically 60670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * three-fourths of the colormap entries are rejected by Heckbert's criterion, 60770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * and we need not compute their distances to individual cells in the subbox. 60870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The speed of this approach is heavily influenced by the subbox size: too 60970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * small means too much overhead, too big loses because Heckbert's criterion 61070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * can't eliminate as many colormap entries. Empirically the best subbox 61170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * size seems to be about 1/512th of the histogram (1/8th in each direction). 61270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 61370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Thomas' article also describes a refined method which is asymptotically 61470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * faster than the brute-force method, but it is also far more complex and 61570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * cannot efficiently be applied to small subboxes. It is therefore not 61670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * useful for programs intended to be portable to DOS machines. On machines 61770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * with plenty of memory, filling the whole histogram in one shot with Thomas' 61870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * refined method might be faster than the present code --- but then again, 61970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * it might not be any faster, and it's certainly more complicated. 62070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 62170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 62270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 62370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* log2(histogram cells in update box) for each axis; this can be adjusted */ 62470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define BOX_C0_LOG (HIST_C0_BITS-3) 62570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define BOX_C1_LOG (HIST_C1_BITS-3) 62670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define BOX_C2_LOG (HIST_C2_BITS-3) 62770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 62870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define BOX_C0_ELEMS (1<<BOX_C0_LOG) /* # of hist cells in update box */ 62970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define BOX_C1_ELEMS (1<<BOX_C1_LOG) 63070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define BOX_C2_ELEMS (1<<BOX_C2_LOG) 63170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 63270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define BOX_C0_SHIFT (C0_SHIFT + BOX_C0_LOG) 63370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define BOX_C1_SHIFT (C1_SHIFT + BOX_C1_LOG) 63470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define BOX_C2_SHIFT (C2_SHIFT + BOX_C2_LOG) 63570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 63670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 63770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 63870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The next three routines implement inverse colormap filling. They could 63970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * all be folded into one big routine, but splitting them up this way saves 64070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * some stack space (the mindist[] and bestdist[] arrays need not coexist) 64170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * and may allow some compilers to produce better code by registerizing more 64270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * inner-loop variables. 64370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 64470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 64570a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineLOCAL(int) 64670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinefind_nearby_colors (j_decompress_ptr cinfo, int minc0, int minc1, int minc2, 64770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPLE colorlist[]) 64870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Locate the colormap entries close enough to an update box to be candidates 64970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * for the nearest entry to some cell(s) in the update box. The update box 65070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * is specified by the center coordinates of its first cell. The number of 65170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * candidate colormap entries is returned, and their colormap indexes are 65270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * placed in colorlist[]. 65370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This routine uses Heckbert's "locally sorted search" criterion to select 65470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * the colors that need further consideration. 65570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 65670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 65770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int numcolors = cinfo->actual_number_of_colors; 65870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int maxc0, maxc1, maxc2; 65970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int centerc0, centerc1, centerc2; 66070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int i, x, ncolors; 66170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine INT32 minmaxdist, min_dist, max_dist, tdist; 66270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine INT32 mindist[MAXNUMCOLORS]; /* min distance to colormap entry i */ 66370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 66470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Compute true coordinates of update box's upper corner and center. 66570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Actually we compute the coordinates of the center of the upper-corner 66670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * histogram cell, which are the upper bounds of the volume we care about. 66770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Note that since ">>" rounds down, the "center" values may be closer to 66870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * min than to max; hence comparisons to them must be "<=", not "<". 66970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 67070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine maxc0 = minc0 + ((1 << BOX_C0_SHIFT) - (1 << C0_SHIFT)); 67170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine centerc0 = (minc0 + maxc0) >> 1; 67270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine maxc1 = minc1 + ((1 << BOX_C1_SHIFT) - (1 << C1_SHIFT)); 67370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine centerc1 = (minc1 + maxc1) >> 1; 67470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine maxc2 = minc2 + ((1 << BOX_C2_SHIFT) - (1 << C2_SHIFT)); 67570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine centerc2 = (minc2 + maxc2) >> 1; 67670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 67770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* For each color in colormap, find: 67870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 1. its minimum squared-distance to any point in the update box 67970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * (zero if color is within update box); 68070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 2. its maximum squared-distance to any point in the update box. 68170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Both of these can be found by considering only the corners of the box. 68270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * We save the minimum distance for each color in mindist[]; 68370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * only the smallest maximum distance is of interest. 68470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 68570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine minmaxdist = 0x7FFFFFFFL; 68670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 68770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (i = 0; i < numcolors; i++) { 68870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* We compute the squared-c0-distance term, then add in the other two. */ 68970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine x = GETJSAMPLE(cinfo->colormap[0][i]); 69070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (x < minc0) { 69170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - minc0) * C0_SCALE; 69270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine min_dist = tdist*tdist; 69370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - maxc0) * C0_SCALE; 69470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine max_dist = tdist*tdist; 69570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else if (x > maxc0) { 69670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - maxc0) * C0_SCALE; 69770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine min_dist = tdist*tdist; 69870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - minc0) * C0_SCALE; 69970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine max_dist = tdist*tdist; 70070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else { 70170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* within cell range so no contribution to min_dist */ 70270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine min_dist = 0; 70370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (x <= centerc0) { 70470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - maxc0) * C0_SCALE; 70570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine max_dist = tdist*tdist; 70670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else { 70770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - minc0) * C0_SCALE; 70870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine max_dist = tdist*tdist; 70970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 71070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 71170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 71270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine x = GETJSAMPLE(cinfo->colormap[1][i]); 71370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (x < minc1) { 71470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - minc1) * C1_SCALE; 71570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine min_dist += tdist*tdist; 71670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - maxc1) * C1_SCALE; 71770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine max_dist += tdist*tdist; 71870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else if (x > maxc1) { 71970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - maxc1) * C1_SCALE; 72070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine min_dist += tdist*tdist; 72170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - minc1) * C1_SCALE; 72270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine max_dist += tdist*tdist; 72370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else { 72470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* within cell range so no contribution to min_dist */ 72570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (x <= centerc1) { 72670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - maxc1) * C1_SCALE; 72770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine max_dist += tdist*tdist; 72870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else { 72970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - minc1) * C1_SCALE; 73070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine max_dist += tdist*tdist; 73170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 73270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 73370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 73470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine x = GETJSAMPLE(cinfo->colormap[2][i]); 73570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (x < minc2) { 73670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - minc2) * C2_SCALE; 73770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine min_dist += tdist*tdist; 73870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - maxc2) * C2_SCALE; 73970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine max_dist += tdist*tdist; 74070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else if (x > maxc2) { 74170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - maxc2) * C2_SCALE; 74270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine min_dist += tdist*tdist; 74370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - minc2) * C2_SCALE; 74470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine max_dist += tdist*tdist; 74570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else { 74670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* within cell range so no contribution to min_dist */ 74770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (x <= centerc2) { 74870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - maxc2) * C2_SCALE; 74970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine max_dist += tdist*tdist; 75070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else { 75170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tdist = (x - minc2) * C2_SCALE; 75270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine max_dist += tdist*tdist; 75370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 75470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 75570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 75670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine mindist[i] = min_dist; /* save away the results */ 75770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (max_dist < minmaxdist) 75870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine minmaxdist = max_dist; 75970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 76070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 76170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Now we know that no cell in the update box is more than minmaxdist 76270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * away from some colormap entry. Therefore, only colors that are 76370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * within minmaxdist of some part of the box need be considered. 76470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 76570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ncolors = 0; 76670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (i = 0; i < numcolors; i++) { 76770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (mindist[i] <= minmaxdist) 76870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine colorlist[ncolors++] = (JSAMPLE) i; 76970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 77070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine return ncolors; 77170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 77270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 77370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 77470a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineLOCAL(void) 77570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinefind_best_colors (j_decompress_ptr cinfo, int minc0, int minc1, int minc2, 77670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int numcolors, JSAMPLE colorlist[], JSAMPLE bestcolor[]) 77770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Find the closest colormap entry for each cell in the update box, 77870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * given the list of candidate colors prepared by find_nearby_colors. 77970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Return the indexes of the closest entries in the bestcolor[] array. 78070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This routine uses Thomas' incremental distance calculation method to 78170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * find the distance from a colormap entry to successive cells in the box. 78270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 78370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 78470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int ic0, ic1, ic2; 78570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int i, icolor; 78670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register INT32 * bptr; /* pointer into bestdist[] array */ 78770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPLE * cptr; /* pointer into bestcolor[] array */ 78870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine INT32 dist0, dist1; /* initial distance values */ 78970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register INT32 dist2; /* current distance in inner loop */ 79070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine INT32 xx0, xx1; /* distance increments */ 79170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register INT32 xx2; 79270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine INT32 inc0, inc1, inc2; /* initial values for increments */ 79370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* This array holds the distance to the nearest-so-far color for each cell */ 79470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine INT32 bestdist[BOX_C0_ELEMS * BOX_C1_ELEMS * BOX_C2_ELEMS]; 79570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 79670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Initialize best-distance for each cell of the update box */ 79770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bptr = bestdist; 79870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (i = BOX_C0_ELEMS*BOX_C1_ELEMS*BOX_C2_ELEMS-1; i >= 0; i--) 79970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine *bptr++ = 0x7FFFFFFFL; 80070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 80170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* For each color selected by find_nearby_colors, 80270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * compute its distance to the center of each cell in the box. 80370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * If that's less than best-so-far, update best distance and color number. 80470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 80570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 80670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Nominal steps between cell centers ("x" in Thomas article) */ 80770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define STEP_C0 ((1 << C0_SHIFT) * C0_SCALE) 80870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define STEP_C1 ((1 << C1_SHIFT) * C1_SCALE) 80970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define STEP_C2 ((1 << C2_SHIFT) * C2_SCALE) 81070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 81170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (i = 0; i < numcolors; i++) { 81270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine icolor = GETJSAMPLE(colorlist[i]); 81370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Compute (square of) distance from minc0/c1/c2 to this color */ 81470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inc0 = (minc0 - GETJSAMPLE(cinfo->colormap[0][icolor])) * C0_SCALE; 81570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dist0 = inc0*inc0; 81670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inc1 = (minc1 - GETJSAMPLE(cinfo->colormap[1][icolor])) * C1_SCALE; 81770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dist0 += inc1*inc1; 81870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inc2 = (minc2 - GETJSAMPLE(cinfo->colormap[2][icolor])) * C2_SCALE; 81970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dist0 += inc2*inc2; 82070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Form the initial difference increments */ 82170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inc0 = inc0 * (2 * STEP_C0) + STEP_C0 * STEP_C0; 82270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inc1 = inc1 * (2 * STEP_C1) + STEP_C1 * STEP_C1; 82370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inc2 = inc2 * (2 * STEP_C2) + STEP_C2 * STEP_C2; 82470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Now loop over all cells in box, updating distance per Thomas method */ 82570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bptr = bestdist; 82670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cptr = bestcolor; 82770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine xx0 = inc0; 82870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (ic0 = BOX_C0_ELEMS-1; ic0 >= 0; ic0--) { 82970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dist1 = dist0; 83070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine xx1 = inc1; 83170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (ic1 = BOX_C1_ELEMS-1; ic1 >= 0; ic1--) { 83270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dist2 = dist1; 83370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine xx2 = inc2; 83470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (ic2 = BOX_C2_ELEMS-1; ic2 >= 0; ic2--) { 83570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (dist2 < *bptr) { 83670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine *bptr = dist2; 83770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine *cptr = (JSAMPLE) icolor; 83870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 83970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dist2 += xx2; 84070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine xx2 += 2 * STEP_C2 * STEP_C2; 84170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bptr++; 84270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cptr++; 84370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 84470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dist1 += xx1; 84570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine xx1 += 2 * STEP_C1 * STEP_C1; 84670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 84770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dist0 += xx0; 84870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine xx0 += 2 * STEP_C0 * STEP_C0; 84970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 85070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 85170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 85270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 85370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 85470a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineLOCAL(void) 85570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinefill_inverse_cmap (j_decompress_ptr cinfo, int c0, int c1, int c2) 85670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Fill the inverse-colormap entries in the update box that contains */ 85770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* histogram cell c0/c1/c2. (Only that one cell MUST be filled, but */ 85870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* we can fill as many others as we wish.) */ 85970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 86070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; 86170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine hist3d histogram = cquantize->histogram; 86270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int minc0, minc1, minc2; /* lower left corner of update box */ 86370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int ic0, ic1, ic2; 86470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register JSAMPLE * cptr; /* pointer into bestcolor[] array */ 86570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register histptr cachep; /* pointer into main cache array */ 86670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* This array lists the candidate colormap indexes. */ 86770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPLE colorlist[MAXNUMCOLORS]; 86870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int numcolors; /* number of candidate colors */ 86970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* This array holds the actually closest colormap index for each cell. */ 87070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPLE bestcolor[BOX_C0_ELEMS * BOX_C1_ELEMS * BOX_C2_ELEMS]; 87170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 87270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Convert cell coordinates to update box ID */ 87370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c0 >>= BOX_C0_LOG; 87470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c1 >>= BOX_C1_LOG; 87570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c2 >>= BOX_C2_LOG; 87670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 87770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Compute true coordinates of update box's origin corner. 87870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Actually we compute the coordinates of the center of the corner 87970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * histogram cell, which are the lower bounds of the volume we care about. 88070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 88170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine minc0 = (c0 << BOX_C0_SHIFT) + ((1 << C0_SHIFT) >> 1); 88270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine minc1 = (c1 << BOX_C1_SHIFT) + ((1 << C1_SHIFT) >> 1); 88370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine minc2 = (c2 << BOX_C2_SHIFT) + ((1 << C2_SHIFT) >> 1); 88470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 88570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Determine which colormap entries are close enough to be candidates 88670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * for the nearest entry to some cell in the update box. 88770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 88870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine numcolors = find_nearby_colors(cinfo, minc0, minc1, minc2, colorlist); 88970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 89070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Determine the actually nearest colors. */ 89170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine find_best_colors(cinfo, minc0, minc1, minc2, numcolors, colorlist, 89270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bestcolor); 89370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 89470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Save the best color numbers (plus 1) in the main cache array */ 89570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c0 <<= BOX_C0_LOG; /* convert ID back to base cell indexes */ 89670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c1 <<= BOX_C1_LOG; 89770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c2 <<= BOX_C2_LOG; 89870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cptr = bestcolor; 89970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (ic0 = 0; ic0 < BOX_C0_ELEMS; ic0++) { 90070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (ic1 = 0; ic1 < BOX_C1_ELEMS; ic1++) { 90170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cachep = & histogram[c0+ic0][c1+ic1][c2]; 90270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (ic2 = 0; ic2 < BOX_C2_ELEMS; ic2++) { 90370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine *cachep++ = (histcell) (GETJSAMPLE(*cptr++) + 1); 90470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 90570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 90670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 90770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 90870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 90970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 91070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 91170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Map some rows of pixels to the output colormapped representation. 91270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 91370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 91470a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineMETHODDEF(void) 91570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinepass2_no_dither (j_decompress_ptr cinfo, 91670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPARRAY input_buf, JSAMPARRAY output_buf, int num_rows) 91770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* This version performs no dithering */ 91870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 91970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; 92070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine hist3d histogram = cquantize->histogram; 92170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register JSAMPROW inptr, outptr; 92270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register histptr cachep; 92370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register int c0, c1, c2; 92470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int row; 92570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JDIMENSION col; 92670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JDIMENSION width = cinfo->output_width; 92770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 92870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (row = 0; row < num_rows; row++) { 92970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inptr = input_buf[row]; 93070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr = output_buf[row]; 93170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (col = width; col > 0; col--) { 93270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* get pixel value and index into the cache */ 93370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c0 = GETJSAMPLE(*inptr++) >> C0_SHIFT; 93470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c1 = GETJSAMPLE(*inptr++) >> C1_SHIFT; 93570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine c2 = GETJSAMPLE(*inptr++) >> C2_SHIFT; 93670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cachep = & histogram[c0][c1][c2]; 93770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* If we have not seen this color before, find nearest colormap entry */ 93870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* and update the cache */ 93970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (*cachep == 0) 94070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine fill_inverse_cmap(cinfo, c0,c1,c2); 94170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Now emit the colormap index for this cell */ 94270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine *outptr++ = (JSAMPLE) (*cachep - 1); 94370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 94470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 94570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 94670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 94770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 94870a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineMETHODDEF(void) 94970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinepass2_fs_dither (j_decompress_ptr cinfo, 95070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPARRAY input_buf, JSAMPARRAY output_buf, int num_rows) 95170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* This version performs Floyd-Steinberg dithering */ 95270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 95370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; 95470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine hist3d histogram = cquantize->histogram; 95570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register LOCFSERROR cur0, cur1, cur2; /* current error or pixel value */ 95670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine LOCFSERROR belowerr0, belowerr1, belowerr2; /* error for pixel below cur */ 95770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine LOCFSERROR bpreverr0, bpreverr1, bpreverr2; /* error for below/prev col */ 95870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register FSERRPTR errorptr; /* => fserrors[] at column before current */ 95970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPROW inptr; /* => current input pixel */ 96070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPROW outptr; /* => current output pixel */ 96170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine histptr cachep; 96270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int dir; /* +1 or -1 depending on direction */ 96370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int dir3; /* 3*dir, for advancing inptr & errorptr */ 96470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int row; 96570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JDIMENSION col; 96670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JDIMENSION width = cinfo->output_width; 96770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPLE *range_limit = cinfo->sample_range_limit; 96870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int *error_limit = cquantize->error_limiter; 96970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPROW colormap0 = cinfo->colormap[0]; 97070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPROW colormap1 = cinfo->colormap[1]; 97170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPROW colormap2 = cinfo->colormap[2]; 97270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine SHIFT_TEMPS 97370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 97470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (row = 0; row < num_rows; row++) { 97570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inptr = input_buf[row]; 97670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr = output_buf[row]; 97770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (cquantize->on_odd_row) { 97870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* work right to left in this row */ 97970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inptr += (width-1) * 3; /* so point to rightmost pixel */ 98070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr += width-1; 98170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dir = -1; 98270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dir3 = -3; 98370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine errorptr = cquantize->fserrors + (width+1)*3; /* => entry after last column */ 98470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->on_odd_row = FALSE; /* flip for next time */ 98570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else { 98670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* work left to right in this row */ 98770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dir = 1; 98870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dir3 = 3; 98970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine errorptr = cquantize->fserrors; /* => entry before first real column */ 99070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->on_odd_row = TRUE; /* flip for next time */ 99170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 99270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Preset error values: no error propagated to first pixel from left */ 99370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur0 = cur1 = cur2 = 0; 99470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* and no error propagated to row below yet */ 99570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine belowerr0 = belowerr1 = belowerr2 = 0; 99670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bpreverr0 = bpreverr1 = bpreverr2 = 0; 99770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 99870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (col = width; col > 0; col--) { 99970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* curN holds the error propagated from the previous pixel on the 100070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * current line. Add the error propagated from the previous line 100170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * to form the complete error correction term for this pixel, and 100270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * round the error term (which is expressed * 16) to an integer. 100370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * RIGHT_SHIFT rounds towards minus infinity, so adding 8 is correct 100470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * for either sign of the error value. 100570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Note: errorptr points to *previous* column's array entry. 100670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 100770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur0 = RIGHT_SHIFT(cur0 + errorptr[dir3+0] + 8, 4); 100870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur1 = RIGHT_SHIFT(cur1 + errorptr[dir3+1] + 8, 4); 100970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur2 = RIGHT_SHIFT(cur2 + errorptr[dir3+2] + 8, 4); 101070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Limit the error using transfer function set by init_error_limit. 101170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * See comments with init_error_limit for rationale. 101270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 101370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur0 = error_limit[cur0]; 101470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur1 = error_limit[cur1]; 101570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur2 = error_limit[cur2]; 101670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Form pixel value + error, and range-limit to 0..MAXJSAMPLE. 101770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The maximum error is +- MAXJSAMPLE (or less with error limiting); 101870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * this sets the required size of the range_limit array. 101970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 102070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur0 += GETJSAMPLE(inptr[0]); 102170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur1 += GETJSAMPLE(inptr[1]); 102270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur2 += GETJSAMPLE(inptr[2]); 102370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur0 = GETJSAMPLE(range_limit[cur0]); 102470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur1 = GETJSAMPLE(range_limit[cur1]); 102570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur2 = GETJSAMPLE(range_limit[cur2]); 102670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Index into the cache with adjusted pixel value */ 102770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cachep = & histogram[cur0>>C0_SHIFT][cur1>>C1_SHIFT][cur2>>C2_SHIFT]; 102870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* If we have not seen this color before, find nearest colormap */ 102970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* entry and update the cache */ 103070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (*cachep == 0) 103170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine fill_inverse_cmap(cinfo, cur0>>C0_SHIFT,cur1>>C1_SHIFT,cur2>>C2_SHIFT); 103270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Now emit the colormap index for this cell */ 103370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine { register int pixcode = *cachep - 1; 103470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine *outptr = (JSAMPLE) pixcode; 103570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Compute representation error for this pixel */ 103670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur0 -= GETJSAMPLE(colormap0[pixcode]); 103770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur1 -= GETJSAMPLE(colormap1[pixcode]); 103870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur2 -= GETJSAMPLE(colormap2[pixcode]); 103970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 104070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Compute error fractions to be propagated to adjacent pixels. 104170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Add these into the running sums, and simultaneously shift the 104270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * next-line error sums left by 1 column. 104370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 104470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine { register LOCFSERROR bnexterr, delta; 104570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 104670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bnexterr = cur0; /* Process component 0 */ 104770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine delta = cur0 * 2; 104870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur0 += delta; /* form error * 3 */ 104970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine errorptr[0] = (FSERROR) (bpreverr0 + cur0); 105070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur0 += delta; /* form error * 5 */ 105170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bpreverr0 = belowerr0 + cur0; 105270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine belowerr0 = bnexterr; 105370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur0 += delta; /* form error * 7 */ 105470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bnexterr = cur1; /* Process component 1 */ 105570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine delta = cur1 * 2; 105670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur1 += delta; /* form error * 3 */ 105770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine errorptr[1] = (FSERROR) (bpreverr1 + cur1); 105870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur1 += delta; /* form error * 5 */ 105970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bpreverr1 = belowerr1 + cur1; 106070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine belowerr1 = bnexterr; 106170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur1 += delta; /* form error * 7 */ 106270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bnexterr = cur2; /* Process component 2 */ 106370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine delta = cur2 * 2; 106470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur2 += delta; /* form error * 3 */ 106570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine errorptr[2] = (FSERROR) (bpreverr2 + cur2); 106670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur2 += delta; /* form error * 5 */ 106770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bpreverr2 = belowerr2 + cur2; 106870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine belowerr2 = bnexterr; 106970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cur2 += delta; /* form error * 7 */ 107070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 107170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* At this point curN contains the 7/16 error value to be propagated 107270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * to the next pixel on the current line, and all the errors for the 107370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * next line have been shifted over. We are therefore ready to move on. 107470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 107570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inptr += dir3; /* Advance pixel pointers to next column */ 107670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr += dir; 107770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine errorptr += dir3; /* advance errorptr to current column */ 107870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 107970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Post-loop cleanup: we must unload the final error values into the 108070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * final fserrors[] entry. Note we need not unload belowerrN because 108170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * it is for the dummy column before or after the actual array. 108270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 108370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine errorptr[0] = (FSERROR) bpreverr0; /* unload prev errs into array */ 108470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine errorptr[1] = (FSERROR) bpreverr1; 108570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine errorptr[2] = (FSERROR) bpreverr2; 108670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 108770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 108870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 108970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 109070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 109170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Initialize the error-limiting transfer function (lookup table). 109270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The raw F-S error computation can potentially compute error values of up to 109370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * +- MAXJSAMPLE. But we want the maximum correction applied to a pixel to be 109470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * much less, otherwise obviously wrong pixels will be created. (Typical 109570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * effects include weird fringes at color-area boundaries, isolated bright 109670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * pixels in a dark area, etc.) The standard advice for avoiding this problem 109770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * is to ensure that the "corners" of the color cube are allocated as output 109870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * colors; then repeated errors in the same direction cannot cause cascading 109970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * error buildup. However, that only prevents the error from getting 110070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * completely out of hand; Aaron Giles reports that error limiting improves 110170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * the results even with corner colors allocated. 110270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * A simple clamping of the error values to about +- MAXJSAMPLE/8 works pretty 110370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * well, but the smoother transfer function used below is even better. Thanks 110470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * to Aaron Giles for this idea. 110570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 110670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 110770a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineLOCAL(void) 110870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkineinit_error_limit (j_decompress_ptr cinfo) 110970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Allocate and fill in the error_limiter table */ 111070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 111170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; 111270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int * table; 111370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int in, out; 111470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 111570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine table = (int *) (*cinfo->mem->alloc_small) 111670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ((j_common_ptr) cinfo, JPOOL_IMAGE, (MAXJSAMPLE*2+1) * SIZEOF(int)); 111770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine table += MAXJSAMPLE; /* so can index -MAXJSAMPLE .. +MAXJSAMPLE */ 111870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->error_limiter = table; 111970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 112070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define STEPSIZE ((MAXJSAMPLE+1)/16) 112170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Map errors 1:1 up to +- MAXJSAMPLE/16 */ 112270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine out = 0; 112370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (in = 0; in < STEPSIZE; in++, out++) { 112470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine table[in] = out; table[-in] = -out; 112570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 112670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Map errors 1:2 up to +- 3*MAXJSAMPLE/16 */ 112770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (; in < STEPSIZE*3; in++, out += (in&1) ? 0 : 1) { 112870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine table[in] = out; table[-in] = -out; 112970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 113070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Clamp the rest to final out value (which is (MAXJSAMPLE+1)/8) */ 113170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (; in <= MAXJSAMPLE; in++) { 113270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine table[in] = out; table[-in] = -out; 113370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 113470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#undef STEPSIZE 113570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 113670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 113770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 113870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 113970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Finish up at the end of each pass. 114070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 114170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 114270a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineMETHODDEF(void) 114370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinefinish_pass1 (j_decompress_ptr cinfo) 114470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 114570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; 114670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 114770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Select the representative colors and fill in cinfo->colormap */ 114870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cinfo->colormap = cquantize->sv_colormap; 114970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine select_colors(cinfo, cquantize->desired); 115070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Force next pass to zero the color index table */ 115170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->needs_zeroed = TRUE; 115270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 115370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 115470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 115570a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineMETHODDEF(void) 115670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinefinish_pass2 (j_decompress_ptr cinfo) 115770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 115870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* no work */ 115970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 116070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 116170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 116270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 116370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Initialize for each processing pass. 116470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 116570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 116670a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineMETHODDEF(void) 116770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinestart_pass_2_quant (j_decompress_ptr cinfo, boolean is_pre_scan) 116870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 116970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; 117070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine hist3d histogram = cquantize->histogram; 117170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int i; 117270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 117370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Only F-S dithering or no dithering is supported. */ 117470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* If user asks for ordered dither, give him F-S. */ 117570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (cinfo->dither_mode != JDITHER_NONE) 117670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cinfo->dither_mode = JDITHER_FS; 117770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 117870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (is_pre_scan) { 117970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Set up method pointers */ 118070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->pub.color_quantize = prescan_quantize; 118170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->pub.finish_pass = finish_pass1; 118270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->needs_zeroed = TRUE; /* Always zero histogram */ 118370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else { 118470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Set up method pointers */ 118570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (cinfo->dither_mode == JDITHER_FS) 118670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->pub.color_quantize = pass2_fs_dither; 118770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine else 118870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->pub.color_quantize = pass2_no_dither; 118970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->pub.finish_pass = finish_pass2; 119070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 119170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Make sure color count is acceptable */ 119270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine i = cinfo->actual_number_of_colors; 119370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (i < 1) 119470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ERREXIT1(cinfo, JERR_QUANT_FEW_COLORS, 1); 119570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (i > MAXNUMCOLORS) 119670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, MAXNUMCOLORS); 119770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 119870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (cinfo->dither_mode == JDITHER_FS) { 119970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine size_t arraysize = (size_t) ((cinfo->output_width + 2) * 120070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine (3 * SIZEOF(FSERROR))); 120170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Allocate Floyd-Steinberg workspace if we didn't already. */ 120270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (cquantize->fserrors == NULL) 120370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->fserrors = (FSERRPTR) (*cinfo->mem->alloc_large) 120470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ((j_common_ptr) cinfo, JPOOL_IMAGE, arraysize); 120570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Initialize the propagated errors to zero. */ 120670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine jzero_far((void FAR *) cquantize->fserrors, arraysize); 120770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Make the error-limit table if we didn't already. */ 120870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (cquantize->error_limiter == NULL) 120970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine init_error_limit(cinfo); 121070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->on_odd_row = FALSE; 121170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 121270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 121370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 121470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Zero the histogram or inverse color map, if necessary */ 121570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (cquantize->needs_zeroed) { 121670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (i = 0; i < HIST_C0_ELEMS; i++) { 121770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine jzero_far((void FAR *) histogram[i], 121870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine HIST_C1_ELEMS*HIST_C2_ELEMS * SIZEOF(histcell)); 121970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 122070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->needs_zeroed = FALSE; 122170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 122270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 122370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 122470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 122570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 122670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Switch to a new external colormap between output passes. 122770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 122870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 122970a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineMETHODDEF(void) 123070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinenew_color_map_2_quant (j_decompress_ptr cinfo) 123170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 123270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; 123370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 123470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Reset the inverse color map */ 123570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->needs_zeroed = TRUE; 123670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 123770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 123870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 123970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 124070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Module initialization routine for 2-pass color quantization. 124170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 124270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 124370a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineGLOBAL(void) 124470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinejinit_2pass_quantizer (j_decompress_ptr cinfo) 124570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 124670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine my_cquantize_ptr cquantize; 124770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int i; 124870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 124970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize = (my_cquantize_ptr) 125070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 125170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine SIZEOF(my_cquantizer)); 125270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cinfo->cquantize = (struct jpeg_color_quantizer *) cquantize; 125370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->pub.start_pass = start_pass_2_quant; 125470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->pub.new_color_map = new_color_map_2_quant; 125570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->fserrors = NULL; /* flag optional arrays not allocated */ 125670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->error_limiter = NULL; 125770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 125870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Make sure jdmaster didn't give me a case I can't handle */ 125970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (cinfo->out_color_components != 3) 126070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ERREXIT(cinfo, JERR_NOTIMPL); 126170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 126270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Allocate the histogram/inverse colormap storage */ 126370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->histogram = (hist3d) (*cinfo->mem->alloc_small) 126470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ((j_common_ptr) cinfo, JPOOL_IMAGE, HIST_C0_ELEMS * SIZEOF(hist2d)); 126570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (i = 0; i < HIST_C0_ELEMS; i++) { 126670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->histogram[i] = (hist2d) (*cinfo->mem->alloc_large) 126770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ((j_common_ptr) cinfo, JPOOL_IMAGE, 126870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine HIST_C1_ELEMS*HIST_C2_ELEMS * SIZEOF(histcell)); 126970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 127070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->needs_zeroed = TRUE; /* histogram is garbage now */ 127170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 127270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Allocate storage for the completed colormap, if required. 127370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * We do this now since it is FAR storage and may affect 127470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * the memory manager's space calculations. 127570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 127670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (cinfo->enable_2pass_quant) { 127770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Make sure color count is acceptable */ 127870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int desired = cinfo->desired_number_of_colors; 127970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Lower bound on # of colors ... somewhat arbitrary as long as > 0 */ 128070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (desired < 8) 128170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ERREXIT1(cinfo, JERR_QUANT_FEW_COLORS, 8); 128270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Make sure colormap indexes can be represented by JSAMPLEs */ 128370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (desired > MAXNUMCOLORS) 128470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, MAXNUMCOLORS); 128570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->sv_colormap = (*cinfo->mem->alloc_sarray) 128670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ((j_common_ptr) cinfo,JPOOL_IMAGE, (JDIMENSION) desired, (JDIMENSION) 3); 128770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->desired = desired; 128870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else 128970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->sv_colormap = NULL; 129070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 129170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Only F-S dithering or no dithering is supported. */ 129270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* If user asks for ordered dither, give him F-S. */ 129370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (cinfo->dither_mode != JDITHER_NONE) 129470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cinfo->dither_mode = JDITHER_FS; 129570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 129670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Allocate Floyd-Steinberg workspace if necessary. 129770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This isn't really needed until pass 2, but again it is FAR storage. 129870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Although we will cope with a later change in dither_mode, 129970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * we do not promise to honor max_memory_to_use if dither_mode changes. 130070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 130170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (cinfo->dither_mode == JDITHER_FS) { 130270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cquantize->fserrors = (FSERRPTR) (*cinfo->mem->alloc_large) 130370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ((j_common_ptr) cinfo, JPOOL_IMAGE, 130470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine (size_t) ((cinfo->output_width + 2) * (3 * SIZEOF(FSERROR)))); 130570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Might as well create the error-limiting table too. */ 130670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine init_error_limit(cinfo); 130770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 130870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 130970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 131070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif /* QUANT_2PASS_SUPPORTED */ 1311