Not the same image after cuda FFT and iFFT

Question

I\'m trying to preform an FFT -> ramp filtering -> iFFT on a 2D image with CUDA. First, as a test I tried to do FFT and iFFt without any filters. After the FFT andthe iFFT the i

Answer 1

CUDA FFT->IFFT sequences require that you divide the resultant values by the number of elements in the transform, if you want to return back to the original data.

From the documentation:

cuFFT performs un-normalized FFTs; that is, performing a forward FFT on an input data set followed by an inverse FFT on the resulting set yields data that is equal to the input, scaled by the number of elements. Scaling either transform by the reciprocal of the size of the data set is left for the user to perform as seen fit.