I’m looking for a tool/software that will compare two bitmap images (pixel graphics) of same size and shape (aspect ratio and orientation) and return their rate of similarity (e.g. in %).

Should run as a terminal command on macOS.

  • I think this needs more criteria. How many % do you consider an image that was flipped? No pixel will match, since they all changed their location. Still, the operation to get there is very simple. Commented Jun 8, 2021 at 10:51
  • How many % do you consider an image that was 1000x1000 and then scaled down to 100x100? Is the difference 99% because 99% of the pixels are lost, or is it 0% because it's the same image, just scaled? Commented Jun 8, 2021 at 10:53
  • The images are basically the same (size etc.), but there are some minor changes from image to image that I want to determine or ignore in my script. E.g. a small ring around an object on images might pulsate a bit. If this is the only difference the tool should tell a difference of 5% e.g. If additionally some text on the image differs, the tool should determine another (higher) percentage.
    – Thomas
    Commented Jun 9, 2021 at 11:35
  • I've edited the question to grasp the details. Please check whether you agree to the edit. Commented Jun 9, 2021 at 12:33
  • What you need should be easily possible. I have implemented such a program myself already. Unfortunately I'm not familiar with macOS and don't do cross platform development. Commented Jun 9, 2021 at 12:35


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