How should I answer a question of someone else in Stack Overflow?
I came across this post:
and wanted to answer:
you can define cimg_use_fftw3 before including CImg, i.e.
#define cimg_use_fftw3 1 #include "CImgpp.h"
Then Cimg will use the fftw3 FFT instead of it's own version which only allows for 2^n-sized (i.e. 1,2,...,1024,2048, etc) inputs. Then call the FFT() method of the CImg struct: