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92 lines
3.5 KiB
92 lines
3.5 KiB
// Copyright 2012 Google Inc. All Rights Reserved. |
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// |
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// This code is licensed under the same terms as WebM: |
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// Software License Agreement: http://www.webmproject.org/license/software/ |
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// Additional IP Rights Grant: http://www.webmproject.org/license/additional/ |
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// ----------------------------------------------------------------------------- |
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// |
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// Image transforms and color space conversion methods for lossless decoder. |
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// |
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// Authors: Vikas Arora (vikaas.arora@gmail.com) |
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// Jyrki Alakuijala (jyrki@google.com) |
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#ifndef WEBP_DSP_LOSSLESS_H_ |
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#define WEBP_DSP_LOSSLESS_H_ |
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#include "../webp/types.h" |
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#include "../webp/decode.h" |
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#if defined(__cplusplus) || defined(c_plusplus) |
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extern "C" { |
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#endif |
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//------------------------------------------------------------------------------ |
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// Image transforms. |
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struct VP8LTransform; // Defined in dec/vp8li.h. |
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// Performs inverse transform of data given transform information, start and end |
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// rows. Transform will be applied to rows [row_start, row_end[. |
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// The *in and *out pointers refer to source and destination data respectively |
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// corresponding to the intermediate row (row_start). |
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void VP8LInverseTransform(const struct VP8LTransform* const transform, |
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int row_start, int row_end, |
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const uint32_t* const in, uint32_t* const out); |
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// Subtracts green from blue and red channels. |
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void VP8LSubtractGreenFromBlueAndRed(uint32_t* argb_data, int num_pixs); |
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void VP8LResidualImage(int width, int height, int bits, |
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uint32_t* const argb, uint32_t* const argb_scratch, |
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uint32_t* const image); |
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void VP8LColorSpaceTransform(int width, int height, int bits, int step, |
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uint32_t* const argb, uint32_t* image); |
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//------------------------------------------------------------------------------ |
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// Color space conversion. |
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// Converts from BGRA to other color spaces. |
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void VP8LConvertFromBGRA(const uint32_t* const in_data, int num_pixels, |
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WEBP_CSP_MODE out_colorspace, uint8_t* const rgba); |
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//------------------------------------------------------------------------------ |
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// Misc methods. |
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// Computes sampled size of 'size' when sampling using 'sampling bits'. |
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static WEBP_INLINE uint32_t VP8LSubSampleSize(uint32_t size, |
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uint32_t sampling_bits) { |
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return (size + (1 << sampling_bits) - 1) >> sampling_bits; |
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} |
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// Faster logarithm for integers. Small values use a look-up table. |
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#define LOG_LOOKUP_IDX_MAX 256 |
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extern const float kLog2Table[LOG_LOOKUP_IDX_MAX]; |
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extern const float kSLog2Table[LOG_LOOKUP_IDX_MAX]; |
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extern float VP8LFastLog2Slow(int v); |
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extern float VP8LFastSLog2Slow(int v); |
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static WEBP_INLINE float VP8LFastLog2(int v) { |
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return (v < LOG_LOOKUP_IDX_MAX) ? kLog2Table[v] : VP8LFastLog2Slow(v); |
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} |
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// Fast calculation of v * log2(v) for integer input. |
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static WEBP_INLINE float VP8LFastSLog2(int v) { |
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return (v < LOG_LOOKUP_IDX_MAX) ? kSLog2Table[v] : VP8LFastSLog2Slow(v); |
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} |
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// In-place difference of each component with mod 256. |
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static WEBP_INLINE uint32_t VP8LSubPixels(uint32_t a, uint32_t b) { |
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const uint32_t alpha_and_green = |
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0x00ff00ffu + (a & 0xff00ff00u) - (b & 0xff00ff00u); |
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const uint32_t red_and_blue = |
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0xff00ff00u + (a & 0x00ff00ffu) - (b & 0x00ff00ffu); |
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return (alpha_and_green & 0xff00ff00u) | (red_and_blue & 0x00ff00ffu); |
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} |
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//------------------------------------------------------------------------------ |
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#if defined(__cplusplus) || defined(c_plusplus) |
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} // extern "C" |
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#endif |
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#endif // WEBP_DSP_LOSSLESS_H_
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