Sequel of a Specified Region

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Tricky on 28 Oct 2011
sorry ImageAnalyst...
Unfortunately I deleted a question answered by ImageAnalyst and accepted by Me.
ImageAnalyst after doing filtering for particular portion is it possible to apply Fourier transform for that portion only to extract frequencies.
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Image Analyst
Image Analyst on 28 Oct 2011
Par for the course. Not only do accepted (or unaccepted) questions I've answered get deleted, but it's been noted that sometimes people accept worse or wrong answers in preference to my better or "right" answers. I'm sure it happens to others also. You weren't the first and you won't be the last.

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Accepted Answer

Image Analyst
Image Analyst on 28 Oct 2011
Yes, of course. You should know however that since your "infinite" image is multiplied by a mask (whatever region zeros out and crops stuff out) your spectrum will be convolved with the FT of the mask shape. Recall that multiplication in the spatial domain corresponds to convolution in the spectral domain.
Image Analyst
Image Analyst on 30 Oct 2011
Yes, but the high pass filtered image was on the original image. I didn't crop it like you did. When you did that, your polygon now fell outside of your new cropped region, unless you take care to subtract an offset from your polygon coordinates. So do that subtraction and then your polygon will now lie over your cropped image, and you can do the masking. Then take the FT and you'll have it. I'd have all the images be single or double so you don't have any problems due to integer quantization.

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