Intra-frame coding method based on rolling hush and block-level intra-frame prediction

Abstract

The invention provides an intra-frame coding method based on a rolling hush and block-level intra-frame prediction of the technical field of image processing. A hash function with a rolling type calculation characteristic and a corresponding rolling type algorithm are selected and utilized to set up an image block lookup table about positional information contained in an image coded area of various image blocks with different pixel contents and hash values of the pixel contents of the image blocks, the image block lookup table is used for judging whether a current image block to be coded is a stored image block in the image block lookup table or not, and two-tuples further serve as coding information of the current image block to be coded or adding is carried out on the image block lookup table. According to the intra-frame coding method, a number of repeated image blocks existing in screen images are fully utilized to further improve intra-frame compressibility, on the premise that calculation expenditures at worst are guaranteed, little calculation expenditures are used for determining whether a prediction block the same as the current image block to be coded exists in the image coded area or not, and when a number of repeated image blocks exist in the screen images, the intra-frame coding method can obtain higher compressibility compared with an existing method.

Description

technical field [0001] The present invention relates to a method in the technical field of image compression processing, in particular to an intra-frame encoding method based on rolling hash and block-level intra-frame prediction. Background technique [0002] Intra-frame coding refers to a type of coding method that does not need to rely on information in other frames when coding a certain area of ​​a frame of image. The intra coding method plays an important role in various video coding and still image coding. [0003] The image sequence processed by video coding technology can be divided into natural scene video (Natural Scene) and screen video (Screen Content) according to its signal source. The former refers to a sequence of images captured from the physical world; the latter refers to a sequence of computer-generated images displayed on a screen. In the encoding of screen video, since the screen video has less movement between frames, its overall compression rate mai...

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Problems solved by technology

[0007] However, none of the above methods can take full advantage of the large number of image block repetitions in the screen image—that is, a block that is exactly the same as the image block to be encoded can often be found in the part of the image area that has been encoded.

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