Do it with the GIMPLUT (Look-Up Tables Effects)Equalize

3.3. Equalize

The "Equalize" operation constructs an appropriate Look-Up Table so that the histogram of the resultant image will be more or less a constant function.

Low colour values will remain lower than higher ones, but the spread of them will change.

Demo

  1. Open the Fifteen-Cent-Ramen-1.jpg picture.
  2. Show its histogram
  3. Equalize it using <Image> Layer Colors Auto Equalize
  4. Looks Better, doesn't it?
  5. Show its histogram.

Written by Shlomi Fish