STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

TECHNICAL FIELD

The present disclosure relates to the field of communications technologies, and in particular, to an intra-frame decoding method and apparatus for a signal component sampling point of an image block and a prediction method and apparatus for a signal component sampling point of an image block.

BACKGROUND

Existing video image coding technologies include an intra-frame coding technology and an inter-frame coding technology. Intra-frame coding is a technology of coding image content using only spatial correlation in a currently coded image block. Inter-frame coding is a technology of coding a currently coded image block using time correlation between the currently coded image block and a coded image block.

To increase intra-frame coding efficiency for an image, an intra-frame prediction technology is first introduced in the H.264 Advanced Video Coding (H.264/AVC) standard to remove spatial information redundancy between a currently coded image block (hereinafter referred to as a current block) and an adjacent coded image block. The High Efficiency Video Coding (HEVC) solution is a new-generation video coding standardization solution currently being studied by the International Organization for Standardization, which inherits and is extended from the intra-frame prediction coding technology in the H.264/AVC standard. A prediction mode set of a chrominance component of an image block may include six optional prediction modes: a direct mode (DM) mode: prediction is performed using a prediction mode of a luminance component of a current block as a prediction mode of a chrominance component of the current block, a linear method (LM) mode: a predicted value of a chrominance component sampling point is calculated based on a correlation model using a reconstructed value of a luminance component sampling point, where a parameter of the correlation model is obtained through calculation according to reconstructed values of luminance component and chrominance component sampling points right above and on the left of a current block, a direct current (DC) mode: an average value of reconstructed values of adjacent chrominance component sampling points right above and on the left of a current block is used as a predicted value of a chrominance component sampling point of the current block, a planar mode: a predicted value of a chrominance component sampling point of a current block is calculated based on an assumption of spatial smooth linear variation of values of chrominance component sampling points, a horizontal mode: a reconstructed value of a chrominance component sampling point on the left side of a current block is used as a predicted value of all chrominance component sampling points in a same row of the current block, and a vertical mode: a reconstructed value of an adjacent chrominance component sampling point right above a current block is used as a predicted value of all chrominance component sampling points in a same column of the current block.

Among the foregoing prediction modes, the DC mode, the vertical mode, the horizontal mode, and the planar mode have a same basic principle as corresponding prediction modes in the H.264/AVC standard, but specific implementation methods are different. The LM mode and the DM mode are two newly added prediction modes.

However, in the existing HEVC solution, a prediction mode set of a chrominance component cannot adapt to the diversity of edge positions of a current block, and in some cases, a prediction effect needs to be improved.

SUMMARY

Embodiments of the present disclosure provide an intra-frame decoding method and apparatus for a signal component sampling point of an image block and a prediction method and apparatus for a signal component sampling point of an image block to improve the accuracy of intra-frame prediction of a current block.

An embodiment of the present disclosure provides a prediction method for a signal component sampling point of an image block, which includes calculating, based on a correlation model, a predicted value of a first signal component sampling point of a current block according to a reconstructed value of a second signal component sampling point of the current block and a parameter of the correlation model, where the parameter of the correlation model is obtained through calculation according to a reconstructed value of a first adjacent signal component sampling point above the current block and a reconstructed value of a second adjacent signal component sampling point above the current block.

An embodiment of the present disclosure further provides a prediction method for a signal component sampling point of an image block, which includes calculating, based on a correlation model, a predicted value of a first signal component sampling point of a current block according to a reconstructed value of a second signal component sampling point of the current block and a parameter of the correlation model, where the parameter of the correlation model is obtained through calculation according to a reconstructed value of a first adjacent signal component sampling point on the left side of the current block and a reconstructed value of a second adjacent signal component sampling point on the left side of the current block.

An embodiment of the present disclosure further provides an intra-frame decoding method for a signal component sampling point of an image block, which includes obtaining, from a video code stream, prediction mode information of a first signal component of a current block, determining a prediction mode of the first signal component of the current block from a prediction mode set of the first signal component of the current block according to the prediction mode information of the first signal component of the current block, where the prediction mode set of the first signal component of the current block includes at least one of a linear model above (LMA) mode and a linear model left (LML) mode, obtaining a predicted value of a first signal component sampling point of the current block according to the prediction mode of the first signal component of the current block, and obtaining a reconstructed value of the first signal component sampling point of the current block according to the predicted value of the first signal component sampling point of the current block.

An embodiment of the present disclosure further provides an intra-frame decoding method for a signal component sampling point of an image block, which includes obtaining, from a video code stream, prediction mode information of a first signal component of a current block, determining a prediction mode of the first signal component of the current block from a prediction mode set of the first signal component of the current block according to the prediction mode information of the first signal component of the current block, where the prediction mode set of the first signal component includes a prediction mode based on a correlation model, and the prediction mode based on the correlation model is determined depending on a prediction mode of a second signal component of the current block, obtaining a predicted value of a first signal component sampling point of the current block according to the prediction mode of the first signal component of the current block, and obtaining a reconstructed value of the first signal component sampling point of the current block according to the predicted value of the first signal component sampling point of the current block.

An embodiment of the present disclosure further provides a prediction apparatus for a signal component sampling point of an image block, which includes a first parameter unit configured to obtain a parameter of a correlation model through calculation according to a reconstructed value of a first adjacent signal component sampling point above a current block and a reconstructed value of a second adjacent signal component sampling point above the current block, and a first predicting unit configured to calculate, based on the correlation model, a predicted value of a first signal component sampling point of the current block according to a reconstructed value of a second signal component sampling point of the current block and the parameter of the correlation model.

An embodiment of the present disclosure further provides a prediction apparatus for a signal component sampling point of an image block, which includes a second parameter unit configured to obtain a parameter of a correlation model through calculation according to a reconstructed value of a first adjacent signal component sampling point on the left side of a current block and a reconstructed value of a second adjacent signal component sampling point on the left side of the current block, and a second predicting unit configured to calculate, based on the correlation model, a predicted value of a first signal component sampling point of the current block according to a reconstructed value of a second signal component sampling point of the current block and the parameter of the correlation model.

An embodiment of the present disclosure further provides an intra-frame decoding apparatus for a signal component sampling point of an image block, which includes a first obtaining unit configured to obtain, from a video code stream, prediction mode information of a first signal component of a current block, a first determining unit configured to determine a prediction mode of the first signal component of the current block from a prediction mode set of the first signal component of the current block according to the prediction mode information of the first signal component of the current block, where the prediction mode set of the first signal component of the current block includes at least one of an LMA mode and an LML mode, a third predicting unit configured to obtain a predicted value of a first signal component sampling point of the current block according to the prediction mode of the first signal component of the current block, and a first calculating unit configured to obtain a reconstructed value of the first signal component sampling point of the current block according to the predicted value of the first signal component sampling point of the current block.

An embodiment of the present disclosure further provides an intra-frame decoding apparatus for a signal component sampling point of an image block, which includes a second obtaining unit configured to obtain, from a video code stream, prediction mode information of a first signal component of a current block, a second determining unit configured to determine a prediction mode of the first signal component of the current block from a prediction mode set of the first signal component of the current block according to the prediction mode information of the first signal component of the current block, where the prediction mode set of the first signal component includes a prediction mode based on a correlation model, and the prediction mode based on the correlation model is determined depending on a prediction mode of a second signal component of the current block, a fourth predicting unit configured to obtain a predicted value of a first signal component sampling point of the current block according to the prediction mode of the first signal component of the current block, and a second calculating unit configured to obtain a reconstructed value of the first signal component sampling point of the current block according to the predicted value of the first signal component sampling point of the current block.

According to the technical solutions provided in the embodiments of the present disclosure, using a technical means of introducing an LMA mode and an LML mode in a process of intra-frame prediction of a current block, the accuracy of intra-frame prediction of the current block is improved.

