Intra-frame coding: Difference between revisions

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{{Short description|Data compression technique}}

{{other uses|IFrame (disambiguation)}}

{{Copypaste|article|url=http://www.cs.cf.ac.uk/Dave/Multimedia/node248.html|date=February 2024}}

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{{refimprove|date=March 2017}}

{{Technical|date=June 2019}}

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'''Intra-frame coding''' is a [[data compression]] technique used within a [[digital video|video]] frame, enabling smaller file sizes and lower bitrates, with little or no loss in quality. Since neighboring pixels within an image are often very similar, rather than storing each pixel independently, the frame image is divided into blocks and the typically minor difference between each pixel can be encoded using fewer bits.

Intra-frame prediction exploits spatial redundancy, i.e. correlation among pixels within one frame, by calculating prediction values through extrapolation from already coded pixels for effective [[delta coding]]. It is one of the two classes of predictive coding methods in [[video coding]]. Its counterpart is inter-frame prediction which exploits temporal redundancy. Temporally independently coded so-called intra frames use only intra coding. The temporally coded [[predicted frame]]s (e.g. MPEG's P- and B-frames) may use intra- as well as inter-frame prediction.