Filter (video)

A video filter is a software component that is used to decode audio and video. Multiple filters can be used in a filter chain, in which each filter receives input from its previous-in-line filter upstream, processes the input and outputs the processed video to its next-in-line filter downstream. Such a configuration can be visualized in a filter graph.

With regards to video encoding three categories of filters can be distinguished:

• prefilters: used before encoding
• intrafilters: used while encoding (and are thus an integral part of a video codec)
• postfilters: used after decoding

Prefilters

Common prefilters include:

• denoising
• resizing (upsampling, downsampling)
• contrast enhancement
• deinterlacing (used to convert interlaced video to progressive video)
• deflicking

Intrafilters

Common intrafilters include:

• deblocking

Postfilters

Common postfilters include:

• deinterlacing
• deblocking
• deringing

See also

• Filter graph

References

• Bovik, Al (ed.). Handbook of Image and Video Processing. San Diego: Academic Press, 2000. ISBN 0-12-119790-5.
• Wang, Yao, Jörn Ostermann, and Ya-Qin Zhang. Video Processing and Communications. Signal Processing Series. Upper Saddle River, N.J.: Prentice Hall, 2002. ISBN 0-13-017547-1.