Interview Questions

How to test and to get the difference between two images which is in the same window?

Software QA/Testing Technical FAQs


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How to test and to get the difference between two images which is in the same window?


Answer1:
How are you doing your comparison? If you are doing it manually, then you should be able to see any major differences. If you are using an automated tool, then there is usually a comparison facility in the tool to do that.

Answer2:
Jasper Software is an open-source utility which can be compiled into C++ and has a imgcmp function which compares JPEG files in very good detail as long as they have the same dimentions and number of components.

Answer3:
Rational has a comparison tool that may be used. I'm sure Mercury has the same tool.

Answer4:
The key question is whether we need a bit-by-bit exact comparison, which the current tools are good at, or an equivalency comparison. What differences between these images are not differences? Near-match comparison has been the subject of a lot of research in printer testing, including an M.Sc. thesis at Florida Tech. It's a tough problem.

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