1. The problem statement, all variables and given/known data I'm working on a Matlab problem for a digital image processing class. The problem is to take an image, then take its 2D-FFT and offset the phase component by pi. Then to take the IFFT of the new DFT using the unmodified magnitude and modified phase. What I got was a matrix of all zeros! -- A black image. I'm not sure if this is the correct result, so I'm here. I notice that when I slowly change the phase offset towards +Pi it fades out. This is a specific problem, but what I really want to know is: In general, how does a phase offset of pi radians to the DFT phase component affect the original image? 2. Relevant equations 3. The attempt at a solution superman is an image we were given for this assignment Matlab Code: superman = imread('superman.png') supermanDFT = fft2(superman); supPhase = wrapTo2Pi(angle(supermanDFT) +pi); supMag = abs(supermanDFT); newSupermanDFT = supMag.*exp(1i*supPhase); newSuperman = ifft2(newSupermanDFT); newSuperman = real(newSuperman); imshow(uint8(newSuperman)) I checked the code by using no phase offset --basically decomposing the image into phase and magnitude reconstructing the DFT with newSupermanDFT = supMag.*exp(1i*supPhase); and taking the inverse and looking at the image. I got the original image as expected. This doesn't guarantee the code is correct, but I have no reason to think its wrong. I'm not really sure what the result should be. :( Thanks for any help.