Intra-prediction device, image encoding device, image decoding device, and program

Abstract

According to the present invention, an intra-prediction unit (181) that performs intra-prediction at the level of blocks obtained by partitioning frame-unit source images comprises: a linear model calculation unit (1811a) that, using luminance component decoded pixel values and chrominance component decoded pixel values at the periphery of a block that is targeted for intra-prediction, calculatesa linear model for luminance component and chrominance component for the target block; a chrominance component prediction unit (1811b) that applies the linear model calculated by the linear model calculation unit (1811a) to luminance component decoded pixels values for the target block and thereby predicts chrominance component pixel values for the target block; and a chrominance component correction unit (1812) that, using decoded pixel values that, of the decoded pixel values at the periphery of the target block, were not used by the linear model calculation unit (1811a) to calculate the linear model, corrects chrominance component predicted pixel values obtained by the chrominance component prediction unit (1811b).

Description

technical field [0001] The present invention relates to an intra prediction device, an image encoding device, an image decoding device, and a program. Background technique [0002] In image coding techniques, intra prediction utilizing spatial correlation within a frame is widely used. In intra prediction, pixel values ​​of a target block are predicted using decoded pixel values ​​located around the block to be predicted (hereinafter referred to as "target block"). [0003] For example, Patent Document 1 discloses an image coding apparatus that uses an intra prediction mode capable of improving the coding efficiency of a color difference signal in an intra predictor that determines an intra prediction mode of a color difference signal for each block of an image. The intra predictor (refer to Patent Document 1). As a related intra prediction mode, there is known an inter-component intra prediction (CCIP: Cross-Component Intra Prediction) in which a pixel value of a chroma c...

AI Technical Summary

Problems solved by technology

However, since the decoded pixels on the upper side and the left side are always used, when the relationship between the signal distribution of the luminance component and the color difference component is different between the upper side and the left side, a correct linear model cannot be calculated. As a result, the color difference component Decreased prediction accuracy

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