quant_levels_dec_utils.c | Explore in Territory

// Copyright 2013 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// Implement gradient smoothing: we replace a current alpha value by its
// surrounding average if it's close enough (that is: the change will be less
// than the minimum distance between two quantized level).
// We use sliding window for computing the 2d moving average.
//
// Author: Skal ([email protected])

#include "src/utils/quant_levels_dec_utils.h"

#include <string.h>   // for memset

#include "src/utils/utils.h"

// #define USE_DITHERING   // uncomment to enable ordered dithering (not vital)

#define FIX …
#define LFIX …
#define LUT_SIZE …

#if defined(USE_DITHERING)

#define DFIX …
#define DSIZE …
// cf. https://en.wikipedia.org/wiki/Ordered_dithering
static const uint8_t kOrderedDither[DSIZE][DSIZE] = {
  {  0,  8,  2, 10 },     // coefficients are in DFIX fixed-point precision
  { 12,  4, 14,  6 },
  {  3, 11,  1,  9 },
  { 15,  7, 13,  5 }
};

#else
#define DFIX …
#endif

SmoothParams;

//------------------------------------------------------------------------------

#define CLIP_8b_MASK …
static WEBP_INLINE uint8_t clip_8b(int v) { … }
#undef CLIP_8b_MASK

// vertical accumulation
static void VFilter(SmoothParams* const p) { … }

// horizontal accumulation. We use mirror replication of missing pixels, as it's
// a little easier to implement (surprisingly).
static void HFilter(SmoothParams* const p) { … }

// emit one filtered output row
static void ApplyFilter(SmoothParams* const p) { … }

//------------------------------------------------------------------------------
// Initialize correction table

static void InitCorrectionLUT(int16_t* const lut, int min_dist) { … }

static void CountLevels(SmoothParams* const p) { … }

// Initialize all params.
static int InitParams(uint8_t* const data, int width, int height, int stride,
                      int radius, SmoothParams* const p) { … }

static void CleanupParams(SmoothParams* const p) { … }

int WebPDequantizeLevels(uint8_t* const data, int width, int height, int stride,
                         int strength) { … }
godot/thirdparty/libwebp/src/utils/quant_levels_dec_utils.c
