This article is missing information about deblocking filters applied to static images rather than videos (e.g. Google's Knusperli). Please expand the article to include this information. Further details may exist on the talk page.(May 2023)
A deblocking filter is a video filter applied to decoded compressed video to improve visual quality and prediction performance by smoothing the sharp edges which can form between macroblocks when block coding techniques are used. The filter aims to improve the appearance of decoded pictures. It is a part of the specification for both the SMPTE VC-1 codec and the ITU H.264 (ISO MPEG-4 AVC) codec.[1][2][3]
In contrast with older MPEG-1/2/4 standards, the H.264 deblocking filter is not an optional additional feature in the decoder.[1][2] It is a feature on both the decoding path and on the encoding path, so that the in-loop effects of the filter are taken into account in reference to macroblocks used for prediction. When a stream is encoded, the filter strength can be selected, or the filter can be switched off entirely. Otherwise, the filter strength is determined by coding modes of adjacent blocks, quantization step size, and the steepness of the luminance gradient between blocks.
The filter operates on the edges of each 4 × 4 or 8 × 8 transform block in the luma and chroma planes of each picture. Each small block's edge is assigned a boundary strength based on whether it is also a macroblock boundary, the coding (intra/inter) of the blocks, whether references (in motion prediction and reference frame choice) differ, and whether it is a luma or chroma edge. Stronger levels of filtering are assigned by this scheme where there is likely to be more distortion. The filter can modify as many as three samples on either side of a given block edge (in the case where an edge is a luma edge that lies between different macroblocks and at least one of them is intra coded). In most cases it can modify one or two samples on either side of the edge (depending on the quantization step size, the tuning of the filter strength by the encoder, the result of an edge detection test, and other factors).
H.263 Annex J deblocking filteredit
Although the concept of an "in loop" deblocking filter is best known in relation to H.264, it was actually also standardized earlier (in a somewhat different form) in the H.263v2 Annex J.[4]
Deblocking filters as post-processorsedit
Prior to H.263 Annex J and H.264, the use of a deblocking filter as a post-processing technique to improve the visual quality of decoded pictures was already a well-known technology. This was particularly true in the video conferencing industry, where the low bit rates used tended to produce significant blocking artifacts that could be substantially reduced by such a filter.
Referencesedit
^ abRecommendation H.264 (08/21) - H.264 : Advanced video coding for generic audiovisual services. ITU-T. 2021-08-22.
^ abList, Peter (July 2003). "Adaptive Deblocking filter" (PDF). IEEE Transactions on Circuits and Systems for Video Technology. 13 (7): 614–619. doi:10.1109/TCSVT.2003.815175.
^"ST 421:2013 - SMPTE Standard - VC-1 Compressed Video Bitstream Format and Decoding Process". St 421:2013: i–493. October 2013. doi:10.5594/SMPTE.ST421.2013. ISBN978-1-61482-770-2.
^ITU-T. "H.263 : Video coding for low bit rate communication". Retrieved 2009-11-02.
January 01, 1970
deblocking, filter, this, article, missing, information, about, deblocking, filters, applied, static, images, rather, than, videos, google, knusperli, please, expand, article, include, this, information, further, details, exist, talk, page, 2023, this, article. This article is missing information about deblocking filters applied to static images rather than videos e g Google s Knusperli Please expand the article to include this information Further details may exist on the talk page May 2023 This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Deblocking filter news newspapers books scholar JSTOR March 2017 Learn how and when to remove this message A deblocking filter is a video filter applied to decoded compressed video to improve visual quality and prediction performance by smoothing the sharp edges which can form between macroblocks when block coding techniques are used The filter aims to improve the appearance of decoded pictures It is a part of the specification for both the SMPTE VC 1 codec and the ITU H 264 ISO MPEG 4 AVC codec 1 2 3 Contents 1 H 264 deblocking filter 2 H 263 Annex J deblocking filter 3 Deblocking filters as post processors 4 ReferencesH 264 deblocking filter editIn contrast with older MPEG 1 2 4 standards the H 264 deblocking filter is not an optional additional feature in the decoder 1 2 It is a feature on both the decoding path and on the encoding path so that the in loop effects of the filter are taken into account in reference to macroblocks used for prediction When a stream is encoded the filter strength can be selected or the filter can be switched off entirely Otherwise the filter strength is determined by coding modes of adjacent blocks quantization step size and the steepness of the luminance gradient between blocks The filter operates on the edges of each 4 4 or 8 8 transform block in the luma and chroma planes of each picture Each small block s edge is assigned a boundary strength based on whether it is also a macroblock boundary the coding intra inter of the blocks whether references in motion prediction and reference frame choice differ and whether it is a luma or chroma edge Stronger levels of filtering are assigned by this scheme where there is likely to be more distortion The filter can modify as many as three samples on either side of a given block edge in the case where an edge is a luma edge that lies between different macroblocks and at least one of them is intra coded In most cases it can modify one or two samples on either side of the edge depending on the quantization step size the tuning of the filter strength by the encoder the result of an edge detection test and other factors H 263 Annex J deblocking filter editAlthough the concept of an in loop deblocking filter is best known in relation to H 264 it was actually also standardized earlier in a somewhat different form in the H 263v2 Annex J 4 Deblocking filters as post processors editPrior to H 263 Annex J and H 264 the use of a deblocking filter as a post processing technique to improve the visual quality of decoded pictures was already a well known technology This was particularly true in the video conferencing industry where the low bit rates used tended to produce significant blocking artifacts that could be substantially reduced by such a filter References edit a b Recommendation H 264 08 21 H 264 Advanced video coding for generic audiovisual services ITU T 2021 08 22 a b List Peter July 2003 Adaptive Deblocking filter PDF IEEE Transactions on Circuits and Systems for Video Technology 13 7 614 619 doi 10 1109 TCSVT 2003 815175 ST 421 2013 SMPTE Standard VC 1 Compressed Video Bitstream Format and Decoding Process St 421 2013 i 493 October 2013 doi 10 5594 SMPTE ST421 2013 ISBN 978 1 61482 770 2 ITU T H 263 Video coding for low bit rate communication Retrieved 2009 11 02 Retrieved from https en wikipedia org w index php title Deblocking filter amp oldid 1213478584, wikipedia, wiki, book, books, library,
