Overview: Quality changes and artifacts

Compression artifacts, generation loss and grain describe different changes to the appearance of encoded pictures.

A soft edge, a block pattern and changing film grain do not all have the same origin. Compression can alter detail within one encode, and further lossy generations can compound those changes. These topics help describe the visible result before blaming resolution, scaling or the display.

• Generation loss
  Generation loss is the additional change introduced when already compressed video is decoded and encoded again with lossy settings.

• Compression artifacts
  Video compression artifacts are visible changes introduced when coding compromises cannot preserve the source's intended appearance.

• Film grain
  Film grain is fine varying picture texture that can be preserved, simplified, or modeled during video encoding.