2D FFT and display power spectrum

I’m using the CUFFT just to do simple 2D real to complex FFT but according to the documentation only the non-redundant complex coefficients are calculated. The problem is I think I’ll need all the coefficients in order to draw a power spectrum? I’ve seen people ask the same questions but I haven’t seen any solutions.
The other question which is not really CUDA related is that how I can draw a power spectrum. Is there an easy way of doing this or do I have to use openGL to do the job?
Thanks in advance for any help.

Pls, could anyone help me out here? Big big thank you for any help.