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How to find whether an image is blurry or not using fft ?

asked 2013-04-18 13:59:17 -0600

Abhay Singh gravatar image

updated 2013-04-19 08:54:52 -0600

Guanta gravatar image

How do I find out whether an image has been blurred using fft?

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answered 2013-04-24 09:48:59 -0600

zerog80 gravatar image

FFT works in frequency domain, blurriness is a spatial characteristic and it's better if you approximate it with the magnitude of horizontal and vertical derivatives as explained here.

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Why should blurriness be a spatial characteristic? E.g. a simple Gauss-filter changes the frequency of the image (low pass filter). And of course blurriness can be computed in the frequency domain, see e.g. one of the first google hits: .

Guanta gravatar imageGuanta ( 2013-04-24 10:20:26 -0600 )edit

answered 2013-04-24 15:45:44 -0600

unxnut gravatar image

If you have the original image available, you can compute the distribution of frequencies in both the original and "blurred" image. If the image has indeed been blurred, you will have fewer high frequency components.

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Asked: 2013-04-18 13:59:17 -0600

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Last updated: Apr 24 '13