[BUG] mergeRectangles hangs

[HoverCatz]

Describe the bug
The program hangs forever.

To Reproduce
Steps to reproduce the behavior:

1. Download attached zip and extract the 2 image files anywhere.
   files.zip
2. Run this code:

ImageComparison comparison = new ImageComparison("output_153.png", "output_154.png");
comparison.createMask(); // hangs forever

Expected behavior
Program should run and exit appropriately.

Screenshots
See attached zip above

Java

• OS: Windows
• openjdk version "1.8.0_252"

Additional context
I managed to trace this to the method mergeRectangles.
I don't know why it hangs, but I debugged it and the (minimum and maximum rectangles) are equal to the image size (width*height).
I (thought I) fixed it (see my comment) by skipping running mergeRectangles in a special scenario:

private List<Rectangle> populateRectangles() {
        long countOfDifferentPixels = populateTheMatrixOfTheDifferences();

        if (countOfDifferentPixels == 0) {
            return emptyList();
        }

        if (isAllowedPercentOfDifferentPixels(countOfDifferentPixels)) {
            return emptyList();
        }
        groupRegions();
        List<Rectangle> rectangles = new ArrayList<>();

        int minX = Integer.MAX_VALUE, minY = Integer.MAX_VALUE, maxX = Integer.MIN_VALUE, maxY = Integer.MIN_VALUE;

        while (counter <= regionCount) {
            Rectangle rectangle = createRectangle();
            if (!rectangle.equals(Rectangle.createDefault()) && rectangle.size() >= minimalRectangleSize) {
                rectangles.add(rectangle);
                Point min = rectangle.getMinPoint();
                Point max = rectangle.getMaxPoint();
                if (min.x < minX) minX = min.x;
                if (min.y < minY) minY = min.y;
                if (max.x > maxX) maxX = max.x;
                if (max.y > maxY) maxY = max.y;
            }
            counter++;
        }

        if (minX == 0 && minY == 0 &&
            maxX == actual.getWidth() - 1 &&
            maxY == actual.getHeight() - 1)
            return Collections.singletonList(new Rectangle(0, 0, maxX, maxY));

        return mergeRectangles(rectangles);
    }

(I don't feel comfortable making a pull request).

[HoverCatz]

Not a permanent fix, not even close.
Just got this issue again somewhere else (2 other frames), it just hangs forever.
Damn thought I found a fix, my bad.
Still needs fixing.

[romankh3]

Hello, @HoverCatz.
Thanks for your contributions.
I will see what can I do with it.

Best regards,
Roman.

[romankh3]

Hi @HoverCatz.
You know, it's totally different images. image-comparison doesn't use for it.

[HoverCatz]

Yes ofc they are different. image-comparison should recognize this and not hang itself...

[romankh3]

I got it, thanks. We need to recognize it and stop comparing

[HoverCatz]

Thank you! 🥇

[romankh3]

@HoverCatz, bug fixed in 4.3.1 version.
Thanks, that you found a bug, investigate the place in which the problem is and create a bug report with provided images.

If you have any ideas of how to improve image-comparison feel free to write me about it.

Best regards,
Roman.

[HoverCatz]

I had a question! Is it possible to implement support to detect when 2 images are "almost" identical? For example randomized JPEG compression on the same image. The original images are the same, but the pixels aren't anymore thanks to compression. Hope you understand! 💯

[romankh3]

Hi, @HoverCatz.
I think this page can help you with you question: https://github.com/romankh3/image-comparison/wiki/Image-Comparison-with-Image-compression