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55 lines
2.2 KiB
55 lines
2.2 KiB
4 months ago
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// Copyright 2019 Google LLC.
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// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
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// Image Diff: Provides a metric for measuring the difference between two encoded images. Prints
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// out a single floating-point number between 0.0 and 1.0; 0 means that the images are identical; 1
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// means that each pixel is maximally different in each channel. A non-zero return value indicates
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// that something went wrong.
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#include "include/codec/SkCodec.h"
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#include "include/core/SkBitmap.h"
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#include "include/core/SkData.h"
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#include "include/core/SkPixmap.h"
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#include "include/core/SkSize.h"
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#include <cmath>
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#include <cstdio>
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int main(int argc, char** argv) {
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if (argc != 3) {
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const char usage[] = "\nUsage:\n %s {FILE1}.png {FILE2}.png\n\n";
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fprintf(stderr, usage, argv[0]);
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return 1;
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}
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SkBitmap bm[2];
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for (int i = 0; i < 2; ++i) {
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const char* path = argv[i + 1];
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if (std::unique_ptr<SkCodec> codec =
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SkCodec::MakeFromData(SkData::MakeFromFileName(path))) {
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bm[i].allocN32Pixels(codec->dimensions().fWidth, codec->dimensions().fHeight);
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if (SkCodec::kSuccess == codec->getPixels(bm[i].pixmap())) {
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continue;
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}
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}
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fprintf(stderr, "\nBad file: '%s'.\n\n", path);
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return 2;
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}
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SkISize dim = bm[0].dimensions();
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if (dim != bm[1].dimensions()) {
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fprintf(stderr, "\nImages must be same size: (%d,%d) != (%d,%d)\n\n",
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dim.fWidth, dim.fHeight, bm[1].dimensions().fWidth, bm[1].dimensions().fHeight);
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return 3;
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}
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int64_t totalDiffs = 0; // Manhattan distance in ARGB color-space.
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for (int y = 0; y < dim.fHeight; ++y) {
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const uint8_t* row1 = reinterpret_cast<const uint8_t*>(bm[0].pixmap().addr32(0, y));
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const uint8_t* row2 = reinterpret_cast<const uint8_t*>(bm[1].pixmap().addr32(0, y));
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for (size_t i = 0; i < (size_t)dim.fWidth * (size_t)4; ++i) {
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totalDiffs += std::abs((int)row1[i] - (int)row2[i]);
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}
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}
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printf("%g\n", (double)totalDiffs /
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((uint64_t)255 * 4 * (uint64_t)dim.fWidth * (uint64_t)dim.fHeight));
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return 0;
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}
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