Image enhancement is one of the first steps in image processing.

As the name suggests, in this technique, the original image is processed so that the resultant image is more suitable than the original for specific applications i.e. the image is enhanced. Image enhancement is a purely subjective processing technique.

By subjective we mean that the desired result varies from person to person.

An image enhancement technique used to process images might be excellent for a person, but the same result might not be good enough for another.

It is also important to know at the outset that image enhancement is a cosmetic procedure i.e. it does not add any extra information to the original image.

It merely improves the subjective quality of the images by working with the existing data. Image enhancement can be done in two domains:

(1) The spatial domain

(2) The frequency domain