351 lines
12 KiB
C
351 lines
12 KiB
C
// Copyright 2016 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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// Simple tool to load two webp/png/jpg/tiff files and compute PSNR/SSIM.
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// This is mostly a wrapper around WebPPictureDistortion().
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//
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/*
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gcc -o get_disto get_disto.c -O3 -I../ -L../examples -L../imageio \
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-lexample_util -limageio_util -limagedec -lwebp -L/opt/local/lib \
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-lpng -lz -ljpeg -ltiff -lm -lpthread
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*/
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//
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// Author: Skal (pascal.massimino@gmail.com)
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "webp/encode.h"
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#include "imageio/image_dec.h"
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#include "imageio/imageio_util.h"
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static size_t ReadPicture(const char* const filename, WebPPicture* const pic,
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int keep_alpha) {
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const uint8_t* data = NULL;
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size_t data_size = 0;
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WebPImageReader reader = NULL;
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int ok = ImgIoUtilReadFile(filename, &data, &data_size);
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if (!ok) goto End;
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pic->use_argb = 1; // force ARGB
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#ifdef HAVE_WINCODEC_H
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// Try to decode the file using WIC falling back to the other readers for
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// e.g., WebP.
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ok = ReadPictureWithWIC(filename, pic, keep_alpha, NULL);
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if (ok) goto End;
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#endif
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reader = WebPGuessImageReader(data, data_size);
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ok = reader(data, data_size, pic, keep_alpha, NULL);
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End:
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if (!ok) {
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fprintf(stderr, "Error! Could not process file %s\n", filename);
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}
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free((void*)data);
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return ok ? data_size : 0;
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}
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static void RescalePlane(uint8_t* plane, int width, int height,
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int x_stride, int y_stride, int max) {
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const uint32_t factor = (max > 0) ? (255u << 16) / max : 0;
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int x, y;
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for (y = 0; y < height; ++y) {
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uint8_t* const ptr = plane + y * y_stride;
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for (x = 0; x < width * x_stride; x += x_stride) {
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const uint32_t diff = (ptr[x] * factor + (1 << 15)) >> 16;
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ptr[x] = diff;
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}
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}
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}
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// Return the max absolute difference.
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static int DiffScaleChannel(uint8_t* src1, int stride1,
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const uint8_t* src2, int stride2,
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int x_stride, int w, int h, int do_scaling) {
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int x, y;
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int max = 0;
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for (y = 0; y < h; ++y) {
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uint8_t* const ptr1 = src1 + y * stride1;
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const uint8_t* const ptr2 = src2 + y * stride2;
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for (x = 0; x < w * x_stride; x += x_stride) {
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const int diff = abs(ptr1[x] - ptr2[x]);
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if (diff > max) max = diff;
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ptr1[x] = diff;
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}
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}
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if (do_scaling) RescalePlane(src1, w, h, x_stride, stride1, max);
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return max;
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}
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//------------------------------------------------------------------------------
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// SSIM calculation. We re-implement these functions here, out of dsp/, to avoid
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// breaking the library's hidden visibility. This code duplication avoids the
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// bigger annoyance of having to open up internal details of libdsp...
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#define SSIM_KERNEL 3 // total size of the kernel: 2 * SSIM_KERNEL + 1
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// struct for accumulating statistical moments
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typedef struct {
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uint32_t w; // sum(w_i) : sum of weights
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uint32_t xm, ym; // sum(w_i * x_i), sum(w_i * y_i)
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uint32_t xxm, xym, yym; // sum(w_i * x_i * x_i), etc.
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} DistoStats;
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// hat-shaped filter. Sum of coefficients is equal to 16.
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static const uint32_t kWeight[2 * SSIM_KERNEL + 1] = { 1, 2, 3, 4, 3, 2, 1 };
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static WEBP_INLINE double SSIMCalculation(const DistoStats* const stats) {
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const uint32_t N = stats->w;
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const uint32_t w2 = N * N;
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const uint32_t C1 = 20 * w2;
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const uint32_t C2 = 60 * w2;
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const uint32_t C3 = 8 * 8 * w2; // 'dark' limit ~= 6
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const uint64_t xmxm = (uint64_t)stats->xm * stats->xm;
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const uint64_t ymym = (uint64_t)stats->ym * stats->ym;
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if (xmxm + ymym >= C3) {
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const int64_t xmym = (int64_t)stats->xm * stats->ym;
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const int64_t sxy = (int64_t)stats->xym * N - xmym; // can be negative
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const uint64_t sxx = (uint64_t)stats->xxm * N - xmxm;
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const uint64_t syy = (uint64_t)stats->yym * N - ymym;
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// we descale by 8 to prevent overflow during the fnum/fden multiply.
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const uint64_t num_S = (2 * (uint64_t)(sxy < 0 ? 0 : sxy) + C2) >> 8;
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const uint64_t den_S = (sxx + syy + C2) >> 8;
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const uint64_t fnum = (2 * xmym + C1) * num_S;
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const uint64_t fden = (xmxm + ymym + C1) * den_S;
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const double r = (double)fnum / fden;
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assert(r >= 0. && r <= 1.0);
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return r;
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}
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return 1.; // area is too dark to contribute meaningfully
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}
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static double SSIMGetClipped(const uint8_t* src1, int stride1,
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const uint8_t* src2, int stride2,
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int xo, int yo, int W, int H) {
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DistoStats stats = { 0, 0, 0, 0, 0, 0 };
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const int ymin = (yo - SSIM_KERNEL < 0) ? 0 : yo - SSIM_KERNEL;
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const int ymax = (yo + SSIM_KERNEL > H - 1) ? H - 1 : yo + SSIM_KERNEL;
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const int xmin = (xo - SSIM_KERNEL < 0) ? 0 : xo - SSIM_KERNEL;
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const int xmax = (xo + SSIM_KERNEL > W - 1) ? W - 1 : xo + SSIM_KERNEL;
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int x, y;
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src1 += ymin * stride1;
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src2 += ymin * stride2;
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for (y = ymin; y <= ymax; ++y, src1 += stride1, src2 += stride2) {
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for (x = xmin; x <= xmax; ++x) {
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const uint32_t w = kWeight[SSIM_KERNEL + x - xo]
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* kWeight[SSIM_KERNEL + y - yo];
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const uint32_t s1 = src1[x];
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const uint32_t s2 = src2[x];
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stats.w += w;
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stats.xm += w * s1;
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stats.ym += w * s2;
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stats.xxm += w * s1 * s1;
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stats.xym += w * s1 * s2;
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stats.yym += w * s2 * s2;
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}
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}
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return SSIMCalculation(&stats);
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}
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// Compute SSIM-score map. Return -1 in case of error, max diff otherwise.
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static int SSIMScaleChannel(uint8_t* src1, int stride1,
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const uint8_t* src2, int stride2,
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int x_stride, int w, int h, int do_scaling) {
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int x, y;
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int max = 0;
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uint8_t* const plane1 = (uint8_t*)malloc(2 * w * h * sizeof(*plane1));
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uint8_t* const plane2 = plane1 + w * h;
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if (plane1 == NULL) return -1;
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// extract plane
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for (y = 0; y < h; ++y) {
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for (x = 0; x < w; ++x) {
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plane1[x + y * w] = src1[x * x_stride + y * stride1];
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plane2[x + y * w] = src2[x * x_stride + y * stride2];
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}
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}
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for (y = 0; y < h; ++y) {
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for (x = 0; x < w; ++x) {
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const double ssim = SSIMGetClipped(plane1, w, plane2, w, x, y, w, h);
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int diff = (int)(255 * (1. - ssim));
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if (diff < 0) {
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diff = 0;
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} else if (diff > max) {
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max = diff;
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}
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src1[x * x_stride + y * stride1] = (diff > 255) ? 255u : (uint8_t)diff;
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}
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}
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free(plane1);
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if (do_scaling) RescalePlane(src1, w, h, x_stride, stride1, max);
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return max;
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}
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// Convert an argb picture to luminance.
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static void ConvertToGray(WebPPicture* const pic) {
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int x, y;
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assert(pic != NULL);
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assert(pic->use_argb);
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for (y = 0; y < pic->height; ++y) {
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uint32_t* const row = &pic->argb[y * pic->argb_stride];
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for (x = 0; x < pic->width; ++x) {
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const uint32_t argb = row[x];
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const uint32_t r = (argb >> 16) & 0xff;
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const uint32_t g = (argb >> 8) & 0xff;
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const uint32_t b = (argb >> 0) & 0xff;
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// We use BT.709 for converting to luminance.
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const uint32_t Y = (uint32_t)(0.2126 * r + 0.7152 * g + 0.0722 * b + .5);
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row[x] = (argb & 0xff000000u) | (Y * 0x010101u);
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}
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}
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}
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static void Help(void) {
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fprintf(stderr,
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"Usage: get_disto [-ssim][-psnr][-alpha] compressed.webp orig.webp\n"
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" -ssim ..... print SSIM distortion\n"
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" -psnr ..... print PSNR distortion (default)\n"
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" -alpha .... preserve alpha plane\n"
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" -h ........ this message\n"
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" -o <file> . save the diff map as a WebP lossless file\n"
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" -scale .... scale the difference map to fit [0..255] range\n"
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" -gray ..... use grayscale for difference map (-scale)\n"
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" Also handles PNG, JPG and TIFF files, in addition to WebP.\n");
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}
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int main(int argc, const char *argv[]) {
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WebPPicture pic1, pic2;
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size_t size1 = 0, size2 = 0;
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int ret = 1;
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float disto[5];
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int type = 0;
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int c;
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int help = 0;
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int keep_alpha = 0;
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int scale = 0;
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int use_gray = 0;
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const char* name1 = NULL;
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const char* name2 = NULL;
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const char* output = NULL;
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if (!WebPPictureInit(&pic1) || !WebPPictureInit(&pic2)) {
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fprintf(stderr, "Can't init pictures\n");
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return 1;
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}
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for (c = 1; c < argc; ++c) {
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if (!strcmp(argv[c], "-ssim")) {
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type = 1;
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} else if (!strcmp(argv[c], "-psnr")) {
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type = 0;
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} else if (!strcmp(argv[c], "-alpha")) {
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keep_alpha = 1;
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} else if (!strcmp(argv[c], "-scale")) {
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scale = 1;
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} else if (!strcmp(argv[c], "-gray")) {
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use_gray = 1;
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} else if (!strcmp(argv[c], "-h")) {
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help = 1;
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ret = 0;
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} else if (!strcmp(argv[c], "-o")) {
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if (++c == argc) {
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fprintf(stderr, "missing file name after %s option.\n", argv[c - 1]);
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goto End;
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}
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output = argv[c];
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} else if (name1 == NULL) {
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name1 = argv[c];
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} else {
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name2 = argv[c];
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}
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}
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if (help || name1 == NULL || name2 == NULL) {
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if (!help) {
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fprintf(stderr, "Error: missing arguments.\n");
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}
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Help();
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goto End;
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}
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size1 = ReadPicture(name1, &pic1, 1);
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size2 = ReadPicture(name2, &pic2, 1);
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if (size1 == 0 || size2 == 0) goto End;
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if (!keep_alpha) {
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WebPBlendAlpha(&pic1, 0x00000000);
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WebPBlendAlpha(&pic2, 0x00000000);
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}
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if (!WebPPictureDistortion(&pic1, &pic2, type, disto)) {
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fprintf(stderr, "Error while computing the distortion.\n");
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goto End;
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}
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printf("%u %.2f %.2f %.2f %.2f %.2f\n",
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(unsigned int)size1,
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disto[4], disto[0], disto[1], disto[2], disto[3]);
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if (output != NULL) {
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uint8_t* data = NULL;
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size_t data_size = 0;
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if (pic1.use_argb != pic2.use_argb) {
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fprintf(stderr, "Pictures are not in the same argb format. "
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"Can't save the difference map.\n");
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goto End;
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}
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if (pic1.use_argb) {
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int n;
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fprintf(stderr, "max differences per channel: ");
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for (n = 0; n < 3; ++n) { // skip the alpha channel
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const int range = (type == 1) ?
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SSIMScaleChannel((uint8_t*)pic1.argb + n, pic1.argb_stride * 4,
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(const uint8_t*)pic2.argb + n, pic2.argb_stride * 4,
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4, pic1.width, pic1.height, scale) :
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DiffScaleChannel((uint8_t*)pic1.argb + n, pic1.argb_stride * 4,
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(const uint8_t*)pic2.argb + n, pic2.argb_stride * 4,
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4, pic1.width, pic1.height, scale);
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if (range < 0) fprintf(stderr, "\nError computing diff map\n");
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fprintf(stderr, "[%d]", range);
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}
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fprintf(stderr, "\n");
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if (use_gray) ConvertToGray(&pic1);
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} else {
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fprintf(stderr, "Can only compute the difference map in ARGB format.\n");
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goto End;
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}
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#if !defined(WEBP_REDUCE_CSP)
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data_size = WebPEncodeLosslessBGRA((const uint8_t*)pic1.argb,
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pic1.width, pic1.height,
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pic1.argb_stride * 4,
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&data);
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if (data_size == 0) {
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fprintf(stderr, "Error during lossless encoding.\n");
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goto End;
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}
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ret = ImgIoUtilWriteFile(output, data, data_size) ? 0 : 1;
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WebPFree(data);
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if (ret) goto End;
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#else
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(void)data;
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(void)data_size;
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fprintf(stderr, "Cannot save the difference map. Please recompile "
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"without the WEBP_REDUCE_CSP flag.\n");
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#endif // WEBP_REDUCE_CSP
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}
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ret = 0;
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End:
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WebPPictureFree(&pic1);
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WebPPictureFree(&pic2);
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return ret;
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}
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