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