A video filter is a software component

Component-based software engineering

Component-based software engineering is a branch of software engineering that emphasizes the separation of concerns in respect of the wide-ranging functionality available throughout a given software system...

 that is used to decode

Decoding

Decoding is the reverse of encoding, which is the process of transforming information from one format into another. Information about decoding can be found in the following:* Digital-to-analog converter, the use of analog circuit for decoding operations...

 audio

Audio

Audio is an electrical or other representation of sound.Audio may also refer to:*Audio, audible content in media production and publishing*AUDIO , an American R&B band of 5 brothers formerly known as TNT Boyz and as B5...

 and video

Video

Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...

. Multiple filters can be used in a filter chain, in which each filter receives input

Input

Input is the term denoting either an entrance or changes which are inserted into a system and which activate/modify a process. It is an abstract concept, used in the modeling, system design and system exploitation...

 from its previous-in-line filter upstream

Upstream

In geography, upstream literally means towards the source of a stream or river, or against the normal direction of water flow.Upstream is the opposite of downstream...

, processes

Video processing

In electrical engineering and computer science, video processing is a particular case of signal processing, which often employs video filters and where the input and output signals are video files or video streams. Video processing techniques are used in television sets, VCRs, DVDs, video codecs,...

 the input and outputs the processed video to its next-in-line filter downstream

Downstream

-Science:* In geography, away from the source of a stream or river* In meteorology, away from the source of an air parcel or mass, along the normal direction of water or air flow* Downstream , in computer or telecommunications networks...

. Such a configuration

Computer configuration

In communications or computer systems, a configuration is an arrangement of functional units according to their nature, number, and chief characteristics. Often, configuration pertains to the choice of hardware, software, firmware, and documentation...

 can be visualized

Software visualization

Software visualization is the static or animated 2-D or 3-D visual representation of information about software systems based on their structure, size, history, or behavior....

 in a filter graph

Filter graph

A filter graph is used in multimedia processing. For example to capture video from a webcam. Filters take input, process it or change the input, and then output the process data. An example of a filter, would be a video codec that takes raw uncompressed video and compresses it using a video...

.

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
  Video codec
  A video codec is a device or software that enables video compression and/or decompression for digital video. The compression usually employs lossy data compression. Historically, video was stored as an analog signal on magnetic tape...
  
  )
• postfilters: used after decoding
  Decoding
  Decoding is the reverse of encoding, which is the process of transforming information from one format into another. Information about decoding can be found in the following:* Digital-to-analog converter, the use of analog circuit for decoding operations...
  
  

Prefilters

Common prefilters include:

• denoising
  Video denoising
  Video denoising is the process of removing noise from a video signal. Video denoising methods can be divided into:* Spatial video denoising methods, where image noise reduction is applied to each frame individually....
  
  
• resizing (upsampling
  Upsampling
  Upsampling is the process of increasing the sampling rate of a signal. For instance, upsampling raster images such as photographs means increasing the resolution of the image....
  
  , downsampling
  Downsampling
  In signal processing, downsampling is the process of reducing the sampling rate of a signal. This is usually done to reduce the data rate or the size of the data....
  
  )
• contrast
  Contrast (vision)
  Contrast is the difference in visual properties that makes an object distinguishable from other objects and the background. In visual perception of the real world, contrast is determined by the difference in the color and brightness of the object and other objects within the same field of view...
  
   enhancement
• deinterlacing
  Deinterlacing
  Deinterlacing is the process of converting interlaced video, such as common analog television signals or 1080i format HDTV signals, into a non-interlaced form....
  
   (used to convert interlaced video to progressive video)
• deflicking
  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 old film...
  
  

Postfilters

Common postfilters include:

• deinterlacing
  Deinterlacing
  Deinterlacing is the process of converting interlaced video, such as common analog television signals or 1080i format HDTV signals, into a non-interlaced form....
  
  
• deblocking
• deringing