Image Enhancement
Consider the PDF pr(r) of an image with normalized gray levels in the range 0 £ r £ 1.
(if the maximum gray level in the given image is 255, the gray levels are normalized to the range (0,1) by dividing by 255).
If we were to apply a transformation s = T(r) to the random variable r, the PDF of the new variable s is given by
Consider the transformation
This is the cumulative (probability) distribution function of r.