Q:

Which Computer Vision / Image Processing technique would solve light imbalance in images?

Given a colour image whose light intensity is dim at the edges and bright in the middle, such as [dim    bright    dim], which computer vision technique would be recommended to correct this imbalance? 
While I believe Histogram Equalisation could help, I've read that it also introduces an unrealistic look to an image by exaggerating the blue channel.
I consider implementing an image processor for this task.

A:

One classic approach is using top hat filtering for leveling uneven illumination. You should perform morphological opening with a large structuring element, then remove the result from the original image.
If you have dark objects on light background you should do bottom hat filtering (dual of top hat filtering): subtract the closing with a large structuring element from the original image.

