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

I came across the following points after some reading.

Contrast stretching is all about increasing the difference between the maximum intensity value in an image and the minimum one. All the rest of the intensity values are spread out between this range.

Histogram equalization is about modifying the intensity values of all the pixels in the image such that the histogram is "flattened" (in reality, the histogram can't be exactly flattened, there would be some peaks and some valleys, but that's a practical problem).

In contrast stretching, there exists a one-to-one relationship of the intensity values between the source image and the target image i.e., the original image can be restored from the contrast-stretched image.

However, once histogram equalization is performed, there is no way of getting back the original image.