MATLAB: IFFT of a Hanning windowed FFT Image

ffthanning windowifftimage processing

Hi, Im Trying to IFFT a Hanning Windowed FFT Image for the code below, to obtain the original image.
w = hanning(434)*hanning(362)'; fft = fftshift(fft2(Pixel_Reassign)); fft = abs(fft); [24 100000]; colormap gray; fftimage = log(fft+1).*w; figure, imshow(fftimage,[]);
Can anyone suggest how i go about this, i've tried to simply IFFT the fft output but i dont seem to get the original image back.
Thanks
Luke

Best Answer

Hello,
You have used your absolute values to plot your image. Now, to reverse the operation you need the full fft results which is a complex matrix for regenerating your input image. Otherwise, you get something else!
Each fft component has value and phase. You shouldn't ignore the phase component which is ignored when you only use absolute values.
This is what you should do:
w = hanning(434)*hanning(362)';
FFT = fftshift(fft2(w)); % complex matrix
FFT_abs = abs(FFT); % absolut values of fft
imagesc(1+log10(FFT_abs)) % show fft results
w_new = ifft2(ifftshift(FFT)); % you need fft not fft_abs
Hope it helps,
Mona
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