Apparatus, a method and a computer program for video coding and decoding

Abstract

A method comprising: obtaining an image block unit comprising samples in color channels of one or two chrominance channels and one luminance channel (); reconstructing samples of said luminance channel of the image block unit (); predicting chrominance samples of at least one color channel of image block unit using at least two cross-component prediction models, each comprising their corresponding linear model parameters, and a luminance threshold value dividing the samples of said luminance channel between said at least two cross-component prediction models (); defining a weighting function for said at least two cross-component prediction models based on location of said two or more chrominance samples and the luminance threshold value (); and applying a smoothing function for samples residing within an offset value from said luminance threshold value, wherein said smoothing function adjusts chrominance values of said samples residing within said offset value by applying said weighting function on the corresponding at least two linear model parameters of the at least two cross-component prediction models ().