A video filter is a
software
Software is a set of computer programs and associated software documentation, documentation and data (computing), data. This is in contrast to Computer hardware, hardware, from which the system is built and which actually performs the work.
...
component
Circuit Component may refer to:
•Are devices that perform functions when they are connected in a circuit.
In engineering, science, and technology Generic systems
* System components, an entity with discrete structure, such as an assem ...
that performs some operation on a multimedia
stream.
Multiple filters can be used in a chain, known as a
''filter graph'', in which each filter receives
input from its
upstream
Upstream may refer to:
* Upstream (bioprocess)
* ''Upstream'' (film), a 1927 film by John Ford
* Upstream (networking)
* ''Upstream'' (newspaper), a newspaper covering the oil and gas industry
* Upstream (petroleum industry)
* Upstream (software ...
filter,
processes
A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic.
Things called a process include:
Business and management
*Business process, activities that produce a specific se ...
the input and outputs the processed video to its
downstream filter.
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With regards to
video encoding three categories of filters can be distinguished:
* prefilters: used before
encoding
In communications and information processing, code is a system of rules to convert information—such as a letter (alphabet), letter, word, sound, image, or gesture—into another form, sometimes data compression, shortened or secrecy, secret ...
* intrafilters: used while encoding (and are thus an integral part of a
video codec
A video codec is software or hardware that compresses and decompresses digital video. In the context of video compression, ''codec'' is a portmanteau of ''encoder'' and ''decoder'', while a device that only compresses is typically called an '' ...
)
* postfilters: used after
decoding
Decoding or decode may refer to: is the process of converting code into plain text or any format that is useful for subsequent processes.
Science and technology
* Decoding, the reverse of encoding
* Parsing, in computer science
* Digital-to-analog ...
Prefilters
Common ''prefilters'' include:
*
denoising
* resizing (
upsampling
In digital signal processing, upsampling, expansion, and interpolation are terms associated with the process of resampling in a multi-rate digital signal processing system. ''Upsampling'' can be synonymous with ''expansion'', or it can describe a ...
,
downsampling In digital signal processing, downsampling, compression, and decimation are terms associated with the process of ''resampling'' in a multi-rate digital signal processing system. Both ''downsampling'' and ''decimation'' can be synonymous with ''com ...
)
*
contrast enhancement
*
deinterlacing
Deinterlacing is the process of converting interlaced video into a non-interlaced or progressive form. Interlaced video signals are commonly found in analog television, digital television (HDTV) when in the 1080i format, some DVD titles, and a ...
(used to convert
interlaced video
Interlaced video (also known as interlaced scan) is a technique for doubling the perceived frame rate of a video display without consuming extra bandwidth. The interlaced signal contains two fields of a video frame captured consecutively. Thi ...
to
progressive video)
*
deflicking
In video processing, deflicking is a filtering operation applied to brightness flicker in video to improve visual quality. The flicker effect can be seen when camera framerate and lighting frequency are not adjusted or in video digitized
D ...
Intrafilters
Common ''intrafilters'' include:
*
deblocking
Postfilters
Common ''postfilters'' include:
*
deinterlacing
Deinterlacing is the process of converting interlaced video into a non-interlaced or progressive form. Interlaced video signals are commonly found in analog television, digital television (HDTV) when in the 1080i format, some DVD titles, and a ...
*
deblocking
*
deringing
See also
*
Filter graph
Notes
References
* Bovik, Al (ed.). ''Handbook of Image and Video Processing''. San Diego: Academic Press, 2000. .
*
Wang, Yao, Jörn Ostermann, and Ya-Qin Zhang. ''Video Processing and Communications''. Signal Processing Series. Upper Saddle River, N.J.: Prentice Hall, 2002. .
Video processing
Video signal
Television terminology
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