105 lines
4.1 KiB
C
105 lines
4.1 KiB
C
// Copyright 2012 Google Inc. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the COPYING file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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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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// Similar to the static method ColorIndexInverseTransform() that is part of
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// lossless.c, but used only for alpha decoding. It takes uint8_t (rather than
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// uint32_t) arguments for 'src' and 'dst'.
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void VP8LColorIndexInverseTransformAlpha(
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const struct VP8LTransform* const transform, int y_start, int y_end,
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const uint8_t* src, uint8_t* dst);
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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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void VP8LBundleColorMap(const uint8_t* const row, int width,
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int xbits, uint32_t* const dst);
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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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