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Ask HN: How can I determine the quality of an image file

by vatsci on 3/18/22, 7:04 AM with 7 comments

I'm building a software to extract text in image. But some uploaded images are blur, and hard to process. So, I need to build a function to determine if an image is low or high quality. How can I do it?

PS: Sorry for my bad english.

  • by version_five on 3/18/22, 7:29 AM

    Downsample it and then up sample and see how different (e.g. mean squared error over the pixels) it is? (Or equivalently (assuming anti-aliasing in the sampling version), apply a low pass filter and compare.

    Those are just heuristics, you'd have to try it to see how well they work.

  • by meta-level on 3/18/22, 7:26 AM

    This is hard to answer in general, although general aspects like contrast and resolution are important of course. Maybe you can provide some background regarding your know how and technology you're going to use.

  • by mardiyah on 3/18/22, 9:25 AM

    google tools of image properties for each OS

    that'd have resolution and bit ratio which I forget how to figure out honestly, not hard to learn in minutes though