lossless.h revision eb525c5499e34cc9c4b825d6d9e75bb07cc06ace
1// Copyright 2012 Google Inc. All Rights Reserved. 2// 3// Use of this source code is governed by a BSD-style license 4// that can be found in the COPYING file in the root of the source 5// tree. An additional intellectual property rights grant can be found 6// in the file PATENTS. All contributing project authors may 7// be found in the AUTHORS file in the root of the source tree. 8// ----------------------------------------------------------------------------- 9// 10// Image transforms and color space conversion methods for lossless decoder. 11// 12// Authors: Vikas Arora (vikaas.arora@gmail.com) 13// Jyrki Alakuijala (jyrki@google.com) 14 15#ifndef WEBP_DSP_LOSSLESS_H_ 16#define WEBP_DSP_LOSSLESS_H_ 17 18#include "../webp/types.h" 19#include "../webp/decode.h" 20 21#if defined(__cplusplus) || defined(c_plusplus) 22extern "C" { 23#endif 24 25//------------------------------------------------------------------------------ 26// Image transforms. 27 28struct VP8LTransform; // Defined in dec/vp8li.h. 29 30// Performs inverse transform of data given transform information, start and end 31// rows. Transform will be applied to rows [row_start, row_end[. 32// The *in and *out pointers refer to source and destination data respectively 33// corresponding to the intermediate row (row_start). 34void VP8LInverseTransform(const struct VP8LTransform* const transform, 35 int row_start, int row_end, 36 const uint32_t* const in, uint32_t* const out); 37 38// Similar to the static method ColorIndexInverseTransform() that is part of 39// lossless.c, but used only for alpha decoding. It takes uint8_t (rather than 40// uint32_t) arguments for 'src' and 'dst'. 41void VP8LColorIndexInverseTransformAlpha( 42 const struct VP8LTransform* const transform, int y_start, int y_end, 43 const uint8_t* src, uint8_t* dst); 44 45// Subtracts green from blue and red channels. 46void VP8LSubtractGreenFromBlueAndRed(uint32_t* argb_data, int num_pixs); 47 48void VP8LResidualImage(int width, int height, int bits, 49 uint32_t* const argb, uint32_t* const argb_scratch, 50 uint32_t* const image); 51 52void VP8LColorSpaceTransform(int width, int height, int bits, int step, 53 uint32_t* const argb, uint32_t* image); 54 55//------------------------------------------------------------------------------ 56// Color space conversion. 57 58// Converts from BGRA to other color spaces. 59void VP8LConvertFromBGRA(const uint32_t* const in_data, int num_pixels, 60 WEBP_CSP_MODE out_colorspace, uint8_t* const rgba); 61 62//------------------------------------------------------------------------------ 63// Misc methods. 64 65// Computes sampled size of 'size' when sampling using 'sampling bits'. 66static WEBP_INLINE uint32_t VP8LSubSampleSize(uint32_t size, 67 uint32_t sampling_bits) { 68 return (size + (1 << sampling_bits) - 1) >> sampling_bits; 69} 70 71// Faster logarithm for integers. Small values use a look-up table. 72#define LOG_LOOKUP_IDX_MAX 256 73extern const float kLog2Table[LOG_LOOKUP_IDX_MAX]; 74extern const float kSLog2Table[LOG_LOOKUP_IDX_MAX]; 75extern float VP8LFastLog2Slow(int v); 76extern float VP8LFastSLog2Slow(int v); 77static WEBP_INLINE float VP8LFastLog2(int v) { 78 return (v < LOG_LOOKUP_IDX_MAX) ? kLog2Table[v] : VP8LFastLog2Slow(v); 79} 80// Fast calculation of v * log2(v) for integer input. 81static WEBP_INLINE float VP8LFastSLog2(int v) { 82 return (v < LOG_LOOKUP_IDX_MAX) ? kSLog2Table[v] : VP8LFastSLog2Slow(v); 83} 84 85 86// In-place difference of each component with mod 256. 87static WEBP_INLINE uint32_t VP8LSubPixels(uint32_t a, uint32_t b) { 88 const uint32_t alpha_and_green = 89 0x00ff00ffu + (a & 0xff00ff00u) - (b & 0xff00ff00u); 90 const uint32_t red_and_blue = 91 0xff00ff00u + (a & 0x00ff00ffu) - (b & 0x00ff00ffu); 92 return (alpha_and_green & 0xff00ff00u) | (red_and_blue & 0x00ff00ffu); 93} 94 95void VP8LBundleColorMap(const uint8_t* const row, int width, 96 int xbits, uint32_t* const dst); 97 98//------------------------------------------------------------------------------ 99 100#if defined(__cplusplus) || defined(c_plusplus) 101} // extern "C" 102#endif 103 104#endif // WEBP_DSP_LOSSLESS_H_ 105