how to decide sigma for FFT based Gaussian filter

Question

I am using a FFT-based guassian low pass filter and was wondering how to decide D0 in equation:

exp(-(D(u,v)^2/2D0^2))

Since I am filtering a 2D image, so how can I relate D0 to pixel size? For gaussian filter in the spatial domain, I typically use the standard deviation of the whole image as sigma (or multiple times of the standard deviation). So, is there a formula that can relate the standard deviation in the spatial domain to D0?

Thanks.

Answer 1

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