Method and apparatus of alf complexity reduction for cross-component taps in video coding

Abstract

A method and apparatus for video coding using simplified ALF (Adaptive Loop Filter) are disclosed. According to the method, input data for a current block comprising a first-colour block and a second-colour block is received, wherein the input data comprises reconstructed first-colour samples of the first-colour block and reconstructed second-colour samples of the second-colour block. Model parameters for cross-component model is derived by using sub-sampled first-colour samples and sub-sampled second-colour samples in a neighbouring area of the current block, the current block, or both. One or more cross-component second-colour samples are derived by applying the cross-component model with the model parameters derived to the reconstructed first-colour samples of the first-colour block. Target ALF processing is applied to the current block to generate a filtered second-colour block, wherein the target ALF processing comprises taps associated with said one or more cross-component second-colour samples. The filtered second-colour block is provided.

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