Remove non uniform illumination

Dear all, I want to remove non-uniform illumination from image. Any body can help me?

Answer 1

[Bjorn Gustavsson]

If you have the Image Processing toolbox there is a demo for how to correct for non-uniform illumination. That might help. If you dont have that one you could try homomorphic filtering. Maybe something like this:

fK = suitable_high_pass_filter_kernel;
im_out = exp(real(ifft(log(Im_in).*fK))) + ... 
mean(Im_in(:));

Or if it is "just" a question of vignetting you could try to correct your image thusly:

im_out = im_in./cos(theta).^n;

where theta is the approximate angle of the pixel lines-of-sight

HTH.

Answer 2

[Bibi Najma]

This link may help : https://blogs.mathworks.com/steve/2013/06/25/homomorphic-filtering-part-1/