Flat field correction is the process of correcting the non-uniform intensity in images. Non-uniform intensity occurs in the images due to lens light fall off (also known as vignetting), non-linear surfaces, and non-uniform lighting.

Flat field correction requires flat field images, also called bright field images, and dark field images from the imaging setup. Flat field images are mandatory for correcting the images.

Flat field images need to be captured using the imaging setup with a bright background or the flat field images can be estimated programmatically using a mathematical model. Once flat field images are captured or estimated, they can be used to correct the non-uniform intensity in the images.

The following illustracion shows an image with non-uniform intensity and the flat field corrected image.