Histogram Equalization

Histogram equalization is a method in image processing that adjusts the contrast of an image using its histogram of pixel intensity values. It works by redistributing the intensity values across the full available range, which spreads out densely clustered values and increases contrast in images that would otherwise look flat, such as x-rays or badly exposed photographs. The technique is simple to implement and reversible when the equalization function is known, but it enhances contrast indiscriminately, which can amplify background noise or create visible banding in images with a limited color depth.