int im_freqflt(in, filtermask, out)
IMAGE *in, *filtermask, *out;
Image sizes should be power of two and less or equal to 512. All images should be one channel square images. Image filtermask is a non-complex one channel image created by im_create_fmask(). Input image can be any type. If input is complex, in and filtermask are multiplied using the function im_cmultim(3) .
If input is not complex then it is transformed into the frequency domain and then it is multiplied with the filtermask. In the latter case the result is inverse fourier transformed and clipped to the input image format using the function im_clip2fmt(3) .