I'm trying to use a Butterworth or Gaussian filter to combine two images in GIMP after using a Fourier plugin to convert the image to the Frequency Domain.
Frequency domain filtering: http://fourier.eng.hmc.edu/e101/lectures/Image_Processing/node8.html
The problem is, I have no clue how to implement/apply that filter in GIMP. There is a Gaussian filter but it's for Gaussian blur, not for placing a Gaussian-shaped gradient in image space. I want something like this: http://retina.anatomy.upenn.edu/~rob/lance/gaus2d.jpg But I need to be able to precisely control the radius. And for Butterworth I would need to control multiple parameters of the shape.
If there were some tool to draw that shape, I could draw it in a layer mask and then merge the layer with another image's FFT, then use reverse FFT to get the combined image.
It's also a huge plus if I can call a function to do this from a Script-Fu script.
Anyone know of a way to achieve this?