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)
22 extern "C" {
23 #endif
24
25 //------------------------------------------------------------------------------
26 // Image transforms.
27
28 struct 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).
34 void 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'.
41 void 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.
46 void VP8LSubtractGreenFromBlueAndRed(uint32_t* argb_data, int num_pixs);
47
48 void VP8LResidualImage(int width, int height, int bits,
49 uint32_t* const argb, uint32_t* const argb_scratch,
50 uint32_t* const image);
51
52 void 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.
59 void 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'.
VP8LSubSampleSize(uint32_t size,uint32_t sampling_bits)66 static 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
73 extern const float kLog2Table[LOG_LOOKUP_IDX_MAX];
74 extern const float kSLog2Table[LOG_LOOKUP_IDX_MAX];
75 extern float VP8LFastLog2Slow(int v);
76 extern float VP8LFastSLog2Slow(int v);
VP8LFastLog2(int v)77 static 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.
VP8LFastSLog2(int v)81 static 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.
VP8LSubPixels(uint32_t a,uint32_t b)87 static 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
95 void 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