Method and apparatus of localized luma prediction mode inheritance for chroma prediction in video coding

Abstract

A method and apparatus of Inter/Intra prediction for a chroma component performed by a video encoder or video decoder are disclosed. According to this method, a current chroma prediction block (e.g. a prediction unit, PU) is divided into multiple chroma prediction sub-blocks (e.g. sub-PUs). A corresponding luma prediction block is identified for each chroma prediction sub-block. A chroma prediction mode for each chroma prediction sub-block is determined from a luma prediction mode associated with the corresponding luma prediction block. A local chroma predictor for the current chroma prediction block is generated by applying a prediction process to the multiple chroma prediction sub-blocks using respective chroma prediction modes. In other words, the prediction process is applied at the chroma prediction sub-block level. After the local chroma predictor is derived, a coding block associated with the current chroma prediction block is encoded or decoded using information comprising the local chroma predictor.