Hal Canary | e5b65d2 | 2019-09-19 11:33:31 -0400 | [diff] [blame] | 1 | // Copyright 2019 Google LLC. |
| 2 | // Use of this source code is governed by a BSD-style license that can be found in the LICENSE file. |
| 3 | |
| 4 | // Image Diff: Provides a metric for measuring the difference between two encoded images. Prints |
| 5 | // out a single floating-point number between 0.0 and 1.0; 0 means that the images are identical; 1 |
| 6 | // means that each pixel is maximally different in each channel. A non-zero return value indicates |
| 7 | // that something went wrong. |
| 8 | |
| 9 | #include "include/codec/SkCodec.h" |
| 10 | #include "include/core/SkBitmap.h" |
| 11 | #include "include/core/SkData.h" |
| 12 | #include "include/core/SkPixmap.h" |
| 13 | #include "include/core/SkSize.h" |
| 14 | |
| 15 | #include <cmath> |
| 16 | #include <cstdio> |
| 17 | |
| 18 | int main(int argc, char** argv) { |
| 19 | if (argc != 3) { |
| 20 | const char usage[] = "\nUsage:\n %s {FILE1}.png {FILE2}.png\n\n"; |
| 21 | fprintf(stderr, usage, argv[0]); |
| 22 | return 1; |
| 23 | } |
| 24 | SkBitmap bm[2]; |
| 25 | for (int i = 0; i < 2; ++i) { |
| 26 | const char* path = argv[i + 1]; |
| 27 | if (std::unique_ptr<SkCodec> codec = |
| 28 | SkCodec::MakeFromData(SkData::MakeFromFileName(path))) { |
| 29 | bm[i].allocN32Pixels(codec->dimensions().fWidth, codec->dimensions().fHeight); |
| 30 | if (SkCodec::kSuccess == codec->getPixels(bm[i].pixmap())) { |
| 31 | continue; |
| 32 | } |
| 33 | } |
| 34 | fprintf(stderr, "\nBad file: '%s'.\n\n", path); |
| 35 | return 2; |
| 36 | } |
| 37 | SkISize dim = bm[0].dimensions(); |
| 38 | if (dim != bm[1].dimensions()) { |
| 39 | fprintf(stderr, "\nImages must be same size: (%d,%d) != (%d,%d)\n\n", |
| 40 | dim.fWidth, dim.fHeight, bm[1].dimensions().fWidth, bm[1].dimensions().fHeight); |
| 41 | return 3; |
| 42 | } |
| 43 | int64_t totalDiffs = 0; // Manhattan distance in ARGB color-space. |
| 44 | for (int y = 0; y < dim.fHeight; ++y) { |
| 45 | const uint8_t* row1 = reinterpret_cast<const uint8_t*>(bm[0].pixmap().addr32(0, y)); |
| 46 | const uint8_t* row2 = reinterpret_cast<const uint8_t*>(bm[1].pixmap().addr32(0, y)); |
| 47 | for (size_t i = 0; i < (size_t)dim.fWidth * (size_t)4; ++i) { |
| 48 | totalDiffs += std::abs((int)row1[i] - (int)row2[i]); |
| 49 | } |
| 50 | } |
| 51 | printf("%g\n", (double)totalDiffs / |
| 52 | ((uint64_t)255 * 4 * (uint64_t)dim.fWidth * (uint64_t)dim.fHeight)); |
| 53 | return 0; |
| 54 | } |