Difference between contrast stretching and histogram equalization

Question

I would like to know the difference between contrast stretching and histogram equalization.

I have tried both using OpenCV and observed the results

Answer 1

Contrast stretching is a linear normalization that stretches an arbitrary interval of the intensities of an image and fits the interval to an another arbitrary interval (usually the target interval is the possible minimum and maximum of the image, like 0 and 255).

Histogram equalization is a nonlinear normalization that stretches the area of histogram with high abundance intensities and compresses the area with low abundance intensities.