Matlab inverse FFT from phase/magnitude only

So I have this image 'I'. I take F = fft2(I) to get the 2D fourier transform. To reconstruct it, I could go ifft2(F).

The problem is, I need to reconstruct this image from only the a) magnitude, and b) phase components of F. How can I separate these two components of the fourier transform, and then reconstruct the image from each?

I tried the abs() and angle() functions to get magnitude and phase, but the phase one won't reconstruct properly.

Help?