Histogram Equalization is a technique used to enhance the contrast of images, but it often changes the brightness too much. To address this issue, researchers have developed methods like BBHE and DSIHE, which divide the image histogram into parts and adjust them separately. These methods aim to improve contrast while keeping the brightness similar to the original image. The researchers compared different histogram equalization techniques and found that BBHE and DSIHE perform better in terms of brightness preservation and contrast enhancement.