Coding UnsharpMask without Fourier functions

Question

I am doing some image processing code in C#, but I cant use any libraries or GNU like code.

The UnsharpMask function depends on Gaussian blur which in turn depends on Fourier Transforms. I wrote code for all this and things are working, but to make a long story short, I need to remove the FFT functions. Is there any way to perform unsharp mask in another way that perhaps does not need FFT?

Answer 1

The Fourier transform part of a Gaussian blur is just an efficient way of doing the convolution with a Gaussian kernel. You can do it using straight forward convolution with a Gaussian kernel of the appropriate standard deviation and size (an odd size kernel around 5-6 times the standard deviation is about right).

See Convolution on Wikipedia.