Add alternate output format to pdfium_diff utility
This format shows how badly mangled the image is vs. the expected,
with a uniform grey indicating no difference at a given position.
-- improve the wording of the help message to suggest why an output
file might not always be produced.
Change-Id: Ib7ea1327ce16f2686a58116e67b9137e9f49b68b
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/82530
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
diff --git a/testing/image_diff/image_diff.cpp b/testing/image_diff/image_diff.cpp
index e7c5681..7257b65 100644
--- a/testing/image_diff/image_diff.cpp
+++ b/testing/image_diff/image_diff.cpp
@@ -20,6 +20,7 @@
#include "core/fxcrt/fx_memory.h"
#include "testing/image_diff/image_diff_png.h"
#include "testing/utils/path_service.h"
+#include "third_party/base/numerics/ranges.h"
#include "third_party/base/numerics/safe_conversions.h"
#if defined(OS_WIN)
@@ -197,16 +198,21 @@
fprintf(
stderr,
"Usage:\n"
- " %s OPTIONS <compare file> <reference file>\n"
- " Compares two files on disk, returning 0 when they are the same;\n"
+ " %s OPTIONS <compare_file> <reference_file>\n"
+ " Compares two files on disk, returning 0 when they are the same.\n"
" Passing \"--histogram\" additionally calculates a diff of the\n"
- " RGBA value histograms. (which is resistant to shifts in layout)\n"
- " Passing \"--reverse-byte-order\" additionally assumes the compare\n"
- " file has BGRA byte ordering.\n"
- " %s --diff <compare file> <reference file> <output file>\n"
- " Compares two files on disk, outputs an image that visualizes the\n"
- " difference to <output file>\n",
- binary_name.c_str(), binary_name.c_str());
+ " RGBA value histograms (which is resistant to shifts in layout).\n"
+ " Passing \"--reverse-byte-order\" additionally assumes the\n"
+ " compare file has BGRA byte ordering.\n\n"
+ " %s --diff <compare_file> <reference_file> <output_file>\n"
+ " Compares two files on disk, and if they differ, outputs an image\n"
+ " to <output_file> that visualizes the differing pixels as red\n"
+ " dots.\n\n"
+ " %s --subtract <compare_file> <reference_file> <output_file>\n"
+ " Compares two files on disk, and if they differ, outputs an image\n"
+ " to <output_file> that visualizes the difference as a scaled\n"
+ " subtraction of pixel values.\n",
+ binary_name.c_str(), binary_name.c_str(), binary_name.c_str());
}
int CompareImages(const std::string& binary_name,
@@ -279,10 +285,48 @@
return same;
}
+bool SubtractImages(const Image& image1, const Image& image2, Image* out) {
+ int w = std::min(image1.w(), image2.w());
+ int h = std::min(image1.h(), image2.h());
+ *out = Image(image1);
+ bool same = (image1.w() == image2.w()) && (image1.h() == image2.h());
+
+ for (int y = 0; y < h; ++y) {
+ for (int x = 0; x < w; ++x) {
+ uint32_t pixel1 = image1.pixel_at(x, y);
+ int32_t r1 = pixel1 & 0xff;
+ int32_t g1 = (pixel1 >> 8) & 0xff;
+ int32_t b1 = (pixel1 >> 16) & 0xff;
+
+ uint32_t pixel2 = image2.pixel_at(x, y);
+ int32_t r2 = pixel2 & 0xff;
+ int32_t g2 = (pixel2 >> 8) & 0xff;
+ int32_t b2 = (pixel2 >> 16) & 0xff;
+
+ int32_t delta_r = r1 - r2;
+ int32_t delta_g = g1 - g2;
+ int32_t delta_b = b1 - b2;
+ same &= (delta_r == 0 && delta_g == 0 && delta_b == 0);
+
+ delta_r = pdfium::clamp(128 + delta_r * 8, 0, 255);
+ delta_g = pdfium::clamp(128 + delta_g * 8, 0, 255);
+ delta_b = pdfium::clamp(128 + delta_b * 8, 0, 255);
+
+ uint32_t new_pixel = RGBA_ALPHA;
+ new_pixel |= delta_r;
+ new_pixel |= (delta_g << 8);
+ new_pixel |= (delta_b << 16);
+ out->set_pixel_at(x, y, new_pixel);
+ }
+ }
+ return same;
+}
+
int DiffImages(const std::string& binary_name,
const std::string& file1,
const std::string& file2,
- const std::string& out_file) {
+ const std::string& out_file,
+ bool do_subtraction) {
Image actual_image;
Image baseline_image;
@@ -298,7 +342,9 @@
}
Image diff_image;
- bool same = CreateImageDiff(baseline_image, actual_image, &diff_image);
+ bool same = do_subtraction
+ ? SubtractImages(baseline_image, actual_image, &diff_image)
+ : CreateImageDiff(baseline_image, actual_image, &diff_image);
if (same)
return kStatusSame;
@@ -324,6 +370,7 @@
bool histograms = false;
bool produce_diff_image = false;
+ bool produce_image_subtraction = false;
bool reverse_byte_order = false;
std::string filename1;
std::string filename2;
@@ -342,6 +389,8 @@
histograms = true;
} else if (strcmp(arg, "--diff") == 0) {
produce_diff_image = true;
+ } else if (strcmp(arg, "--subtract") == 0) {
+ produce_image_subtraction = true;
} else if (strcmp(arg, "--reverse-byte-order") == 0) {
reverse_byte_order = true;
}
@@ -353,9 +402,10 @@
if (i < argc)
diff_filename = argv[i++];
- if (produce_diff_image) {
+ if (produce_diff_image || produce_image_subtraction) {
if (!diff_filename.empty()) {
- return DiffImages(binary_name, filename1, filename2, diff_filename);
+ return DiffImages(binary_name, filename1, filename2, diff_filename,
+ produce_image_subtraction);
}
} else if (!filename2.empty()) {
return CompareImages(binary_name, filename1, filename2, histograms,
