Piecewise modeling for linear component sample prediction

摘要

A linear model for obtaining a first-component sample for a first-component block from an associated reconstructed second-component sample of a second-component block in the same frame is derived. The derivation comprises determining at least three points, each point, A, T and B, being defined by two variables, the first variable corresponding to a second-component sample value, the second variable corresponding to a first-component sample value, based on reconstructed samples of both the first-component and the second-component. Parameters, α and β, of each of a plurality of linear equations are determined, each equation representing a straight line passing through two adjacent points of said M points, and a piecewise linear model defined by the parameters of the said straight lines is derived. Also claimed are methods in which different criteria are used to determine if more than one linear equation should be used in determining the model. The methods may be used to predict chroma component samples from reconstructed luma component samples in video coding.