Overview: Image cleanup

Image-cleanup filters alter bands, noise or edge contrast through distinct processing goals.

Debanding addresses visible steps in gradients, denoising addresses unwanted variation, and sharpening changes perceived edge contrast. Each operation responds to a different feature of the image. Identifying that feature first makes the filter's effect easier to judge and keeps several superficially similar “improvements” from being confused.

• Debanding
  Debanding estimates smoother picture values where a gradient has collapsed into visible steps, while attempting to preserve genuine structure.

• Video denoising
  Video denoising estimates picture content from noisy observations using spatial or temporal evidence while deciding which variations to preserve.

• Video sharpening
  Video sharpening increases selected local picture contrast, often by adding a correction derived from a blurred version of the image.