lossless.h revision a2415724fb3466168b2af5b08bd94ba732c0e753
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) 20extern "C" { 21#endif 22 23//------------------------------------------------------------------------------ 24// Image transforms. 25 26struct 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). 32void 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. 37void VP8LSubtractGreenFromBlueAndRed(uint32_t* argb_data, int num_pixs); 38 39void VP8LResidualImage(int width, int height, int bits, 40 uint32_t* const argb, uint32_t* const argb_scratch, 41 uint32_t* const image); 42 43void 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. 50void 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'. 57static 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. 63float VP8LFastLog2(int v); 64// Fast calculation of v * log2(v) for integer input. 65static WEBP_INLINE float VP8LFastSLog2(int v) { return VP8LFastLog2(v) * v; } 66 67// In-place difference of each component with mod 256. 68static 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