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// 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.
// -----------------------------------------------------------------------------
//
// WebPPicture tools for measuring distortion
//
// Author: Skal (pascal.massimino@gmail.com)
#include <math.h>
#include <stdlib.h>
#include "./vp8enci.h"
#include "../utils/utils.h"
//------------------------------------------------------------------------------
// local-min distortion
//
// For every pixel in the *reference* picture, we search for the local best
// match in the compressed image. This is not a symmetrical measure.
#define RADIUS 2 // search radius. Shouldn't be too large.
static void AccumulateLSIM(const uint8_t* src, int src_stride,
const uint8_t* ref, int ref_stride,
int w, int h, VP8DistoStats* stats) {
int x, y;
double total_sse = 0.;
for (y = 0; y < h; ++y) {
const int y_0 = (y - RADIUS < 0) ? 0 : y - RADIUS;
const int y_1 = (y + RADIUS + 1 >= h) ? h : y + RADIUS + 1;
for (x = 0; x < w; ++x) {
const int x_0 = (x - RADIUS < 0) ? 0 : x - RADIUS;
const int x_1 = (x + RADIUS + 1 >= w) ? w : x + RADIUS + 1;
double best_sse = 255. * 255.;
const double value = (double)ref[y * ref_stride + x];
int i, j;
for (j = y_0; j < y_1; ++j) {
const uint8_t* const s = src + j * src_stride;
for (i = x_0; i < x_1; ++i) {
const double diff = s[i] - value;
const double sse = diff * diff;
if (sse < best_sse) best_sse = sse;
}
}
total_sse += best_sse;
}
}
stats->w = w * h;
stats->xm = 0;
stats->ym = 0;
stats->xxm = total_sse;
stats->yym = 0;
stats->xxm = 0;
}
#undef RADIUS
//------------------------------------------------------------------------------
// Distortion
// Max value returned in case of exact similarity.
static const double kMinDistortion_dB = 99.;
static float GetPSNR(const double v) {
return (float)((v > 0.) ? -4.3429448 * log(v / (255 * 255.))
: kMinDistortion_dB);
}
int WebPPictureDistortion(const WebPPicture* src, const WebPPicture* ref,
int type, float result[5]) {
VP8DistoStats stats[5];
int w, h;
memset(stats, 0, sizeof(stats));
VP8SSIMDspInit();
if (src == NULL || ref == NULL ||
src->width != ref->width || src->height != ref->height ||
src->use_argb != ref->use_argb || result == NULL) {
return 0;
}
w = src->width;
h = src->height;
if (src->use_argb == 1) {
if (src->argb == NULL || ref->argb == NULL) {
return 0;
} else {
int i, j, c;
uint8_t* tmp1, *tmp2;
uint8_t* const tmp_plane =
(uint8_t*)WebPSafeMalloc(2ULL * w * h, sizeof(*tmp_plane));
if (tmp_plane == NULL) return 0;
tmp1 = tmp_plane;
tmp2 = tmp_plane + w * h;
for (c = 0; c < 4; ++c) {
for (j = 0; j < h; ++j) {
for (i = 0; i < w; ++i) {
tmp1[j * w + i] = src->argb[i + j * src->argb_stride] >> (c * 8);
tmp2[j * w + i] = ref->argb[i + j * ref->argb_stride] >> (c * 8);
}
}
if (type >= 2) {
AccumulateLSIM(tmp1, w, tmp2, w, w, h, &stats[c]);
} else {
VP8SSIMAccumulatePlane(tmp1, w, tmp2, w, w, h, &stats[c]);
}
}
free(tmp_plane);
}
} else {
int has_alpha, uv_w, uv_h;
if (src->y == NULL || ref->y == NULL ||
src->u == NULL || ref->u == NULL ||
src->v == NULL || ref->v == NULL) {
return 0;
}
has_alpha = !!(src->colorspace & WEBP_CSP_ALPHA_BIT);
if (has_alpha != !!(ref->colorspace & WEBP_CSP_ALPHA_BIT) ||
(has_alpha && (src->a == NULL || ref->a == NULL))) {
return 0;
}
uv_w = (src->width + 1) >> 1;
uv_h = (src->height + 1) >> 1;
if (type >= 2) {
AccumulateLSIM(src->y, src->y_stride, ref->y, ref->y_stride,
w, h, &stats[0]);
AccumulateLSIM(src->u, src->uv_stride, ref->u, ref->uv_stride,
uv_w, uv_h, &stats[1]);
AccumulateLSIM(src->v, src->uv_stride, ref->v, ref->uv_stride,
uv_w, uv_h, &stats[2]);
if (has_alpha) {
AccumulateLSIM(src->a, src->a_stride, ref->a, ref->a_stride,
w, h, &stats[3]);
}
} else {
VP8SSIMAccumulatePlane(src->y, src->y_stride,
ref->y, ref->y_stride,
w, h, &stats[0]);
VP8SSIMAccumulatePlane(src->u, src->uv_stride,
ref->u, ref->uv_stride,
uv_w, uv_h, &stats[1]);
VP8SSIMAccumulatePlane(src->v, src->uv_stride,
ref->v, ref->uv_stride,
uv_w, uv_h, &stats[2]);
if (has_alpha) {
VP8SSIMAccumulatePlane(src->a, src->a_stride,
ref->a, ref->a_stride,
w, h, &stats[3]);
}
}
}
// Final stat calculations.
{
int c;
for (c = 0; c <= 4; ++c) {
if (type == 1) {
const double v = VP8SSIMGet(&stats[c]);
result[c] = (float)((v < 1.) ? -10.0 * log10(1. - v)
: kMinDistortion_dB);
} else {
const double v = VP8SSIMGetSquaredError(&stats[c]);
result[c] = GetPSNR(v);
}
// Accumulate forward
if (c < 4) VP8SSIMAddStats(&stats[c], &stats[4]);
}
}
return 1;
}
//------------------------------------------------------------------------------
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