near_lossless_enc.c | Explore in Territory

// Copyright 2014 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.
// -----------------------------------------------------------------------------
//
// Near-lossless image preprocessing adjusts pixel values to help
// compressibility with a guarantee of maximum deviation between original and
// resulting pixel values.
//
// Author: Jyrki Alakuijala ([email protected])
// Converted to C by Aleksander Kramarz ([email protected])

#include <assert.h>
#include <stdlib.h>

#include "src/dsp/lossless_common.h"
#include "src/utils/utils.h"
#include "src/enc/vp8li_enc.h"

#if (WEBP_NEAR_LOSSLESS == 1)

#define MIN_DIM_FOR_NEAR_LOSSLESS …
#define MAX_LIMIT_BITS …

// Quantizes the value up or down to a multiple of 1<<bits (or to 255),
// choosing the closer one, resolving ties using bankers' rounding.
static uint32_t FindClosestDiscretized(uint32_t a, int bits) { … }

// Applies FindClosestDiscretized to all channels of pixel.
static uint32_t ClosestDiscretizedArgb(uint32_t a, int bits) { … }

// Checks if distance between corresponding channel values of pixels a and b
// is within the given limit.
static int IsNear(uint32_t a, uint32_t b, int limit) { … }

static int IsSmooth(const uint32_t* const prev_row,
                    const uint32_t* const curr_row,
                    const uint32_t* const next_row,
                    int ix, int limit) { … }

// Adjusts pixel values of image with given maximum error.
static void NearLossless(int xsize, int ysize, const uint32_t* argb_src,
                         int stride, int limit_bits, uint32_t* copy_buffer,
                         uint32_t* argb_dst) { … }

int VP8ApplyNearLossless(const WebPPicture* const picture, int quality,
                         uint32_t* const argb_dst) { … }
#else  // (WEBP_NEAR_LOSSLESS == 1)

// Define a stub to suppress compiler warnings.
extern void VP8LNearLosslessStub(void);
void VP8LNearLosslessStub(void) {}

#endif  // (WEBP_NEAR_LOSSLESS == 1)
godot/thirdparty/libwebp/src/enc/near_lossless_enc.c
