Is it possible to reconstruct an image using its magnitude only?
Re-construction using just the magnitude (and an assumed phase of zero) will only work for exactly symmetric images.  The phase is needed to make the top look different from the bottom and left look different from the right side of the image, etc.  

That's because all the cosine waveform DFT basis vectors are exactly symmetric around the center of an FFT or DFT window.  Thus, unshifted, they can only reconstruct a symmetric result.  You could shift the phase of each basis vector randomly (or 90 degrees to make them all sinewaves) but, without knowing the phase shifts of the original image's DFT (or guessing right), you would just get another garbage result.