Flat field correction is a technique that improves image quality by removing artifacts that are caused by variations in the pixel-to-pixel sensitivity of the camera (image sensor) and/or illuminator. Additionally, flat field correction can remove distortions in the optical path (including small dirt particles on the image sensor). It is a standard calibration procedure in contemporary digital cameras.
For the overview camera, flat field correction uses a fixed flat field image stored on disk to adjust the overview image.
For the slide camera, flat field correction uses either a fixed flat field image stored on disk or captures a new flat field image for each scan depending on the Auto Flat Field setting. Refer to “Auto Flat Field” on page 57 for more information.
Flat field correction eliminates or reduces gradient effects of the illuminator and objective as well as optical distortions like dirt on the image sensor. It will not eliminate the effects of dirt or debris on the slide or cover slip.