1 // Copyright 2012 Google Inc. All Rights Reserved.
2 //
3 // This code is licensed under the same terms as WebM:
4 // Software License Agreement: http://www.webmproject.org/license/software/
5 // Additional IP Rights Grant: http://www.webmproject.org/license/additional/
6 // -----------------------------------------------------------------------------
7 //
8 // Image transforms and color space conversion methods for lossless decoder.
9 //
10 // Authors: Vikas Arora (vikaas.arora@gmail.com)
11 // Jyrki Alakuijala (jyrki@google.com)
12
13 #ifndef WEBP_DSP_LOSSLESS_H_
14 #define WEBP_DSP_LOSSLESS_H_
15
16 #include "webp/types.h"
17 #include "webp/decode.h"
18
19 #if defined(__cplusplus) || defined(c_plusplus)
20 extern "C" {
21 #endif
22
23 //------------------------------------------------------------------------------
24 // Image transforms.
25
26 struct VP8LTransform; // Defined in dec/vp8li.h.
27
28 // Performs inverse transform of data given transform information, start and end
29 // rows. Transform will be applied to rows [row_start, row_end[.
30 // The *in and *out pointers refer to source and destination data respectively
31 // corresponding to the intermediate row (row_start).
32 void VP8LInverseTransform(const struct VP8LTransform* const transform,
33 int row_start, int row_end,
34 const uint32_t* const in, uint32_t* const out);
35
36 // Subtracts green from blue and red channels.
37 void VP8LSubtractGreenFromBlueAndRed(uint32_t* argb_data, int num_pixs);
38
39 void VP8LResidualImage(int width, int height, int bits,
40 uint32_t* const argb, uint32_t* const argb_scratch,
41 uint32_t* const image);
42
43 void VP8LColorSpaceTransform(int width, int height, int bits, int step,
44 uint32_t* const argb, uint32_t* image);
45
46 //------------------------------------------------------------------------------
47 // Color space conversion.
48
49 // Converts from BGRA to other color spaces.
50 void VP8LConvertFromBGRA(const uint32_t* const in_data, int num_pixels,
51 WEBP_CSP_MODE out_colorspace, uint8_t* const rgba);
52
53 //------------------------------------------------------------------------------
54 // Misc methods.
55
56 // Computes sampled size of 'size' when sampling using 'sampling bits'.
VP8LSubSampleSize(uint32_t size,uint32_t sampling_bits)57 static WEBP_INLINE uint32_t VP8LSubSampleSize(uint32_t size,
58 uint32_t sampling_bits) {
59 return (size + (1 << sampling_bits) - 1) >> sampling_bits;
60 }
61
62 // Faster logarithm for integers, with the property of log2(0) == 0.
63 float VP8LFastLog2(int v);
64 // Fast calculation of v * log2(v) for integer input.
VP8LFastSLog2(int v)65 static WEBP_INLINE float VP8LFastSLog2(int v) { return VP8LFastLog2(v) * v; }
66
67 // In-place difference of each component with mod 256.
VP8LSubPixels(uint32_t a,uint32_t b)68 static WEBP_INLINE uint32_t VP8LSubPixels(uint32_t a, uint32_t b) {
69 const uint32_t alpha_and_green =
70 0x00ff00ffu + (a & 0xff00ff00u) - (b & 0xff00ff00u);
71 const uint32_t red_and_blue =
72 0xff00ff00u + (a & 0x00ff00ffu) - (b & 0x00ff00ffu);
73 return (alpha_and_green & 0xff00ff00u) | (red_and_blue & 0x00ff00ffu);
74 }
75
76 //------------------------------------------------------------------------------
77
78 #if defined(__cplusplus) || defined(c_plusplus)
79 } // extern "C"
80 #endif
81
82 #endif // WEBP_DSP_LOSSLESS_H_
83