Contrast is the contradiction in luminance or colour that makes an object distinguishable, and is determined by the difference in the colour and brightness of the object and other objects within the same field of view. The human eye shows high sensitivity towards contrast and it is an important aspect of vision and us being able to see "well".

Image contrasting is the process of changing the contrast spectrum of an existing image to focus it the band which is best suited for human vision, which allows us to clearly distinguish the components of the image.

In the case of low-vision people, image contrasting turns out to be one of the major factors that can impact their ability to see. A well contrasted image will allow them to view the contents of the image well, and if there's text, allow them to read it better.