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

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

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

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

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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: http://www.filiprooms.be/publications/accvpap.pdf .

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Asked: **
2013-04-18 13:59:17 -0500
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Seen: **2,758 times**

Last updated: **Apr 24 '13**

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