Simplifications of cross-component linear model

A coding device comprising:

• one or more processors;
• memory coupled to the one or more processors;
• and
• a plurality of programs stored in the memory that, when executed by the one or more processors, cause the one or more processors to perform a method for decoding a video signal comprising:
• obtaining a video bitstream comprising a plurality of video blocks in a video frame, wherein each video block comprises at least one lama block and at least one chroma block;
• reconstructing a luma block corresponding to a chroma block in a current video block, wherein the luma block is adjacent to a plurality of reconstructed neighboring luma samples, and wherein the chroma block is adjacent to a plurality of reconstructed neighboring chroma samples;
• identifying, from a sub-group of the plurality of reconstructed neighboring luma samples, at least one maximum luma sample, wherein the at least one maximum luma sample corresponds to a first reconstructed chroma sample of the plurality of reconstructed neighboring chroma samples, the sub-group is composed of a predefined number of the reconstructed neighboring luma samples among the plurality of reconstructed neighboring luma samples;
• identifying, from the sub-group of the plurality of reconstructed neighboring luma samples, at least one minimum luma samples, wherein the at least one minimum luma sample corresponds to a second reconstructed chroma sample of the plurality of reconstructed neighboring chroma samples;
• fitting a linear model through the at least one maximum luma sample, the at least one minimum luma sample, the first reconstructed chroma sample, and the second reconstructed chroma sample;
• predicting chroma samples of the chroma block by applying the linear model to the luma samples of the luma block;
• and
• reconstructing the chroma block based on the predicted chroma samples.

A non-transitory computer readable storage medium storing a plurality of programs for execution by a computing device having one or more processors, wherein the plurality of programs, when executed by the one or more processors, cause the computing device to receive bitstream and perform, based on the bitstream, a method for decoding a video signal comprising:

• obtaining a video bitstream comprising a plurality of video blocks in a video frame, wherein each video block comprises at least one luma block and at least one chroma block;
• reconstructing a luma block corresponding to a chroma block in a current video block, wherein the luma block is adjacent to a plurality of reconstructed neighboring luma samples, and wherein the chroma block is adjacent to a plurality of reconstructed neighboring chroma samples;
• identifying, from a sub-group of the plurality of reconstructed neighboring luma samples, at least one maximum luma sample, wherein the at least one maximum luma sample corresponds to a first reconstructed chroma sample of the plurality of reconstructed neighboring chroma samples, the sub-group is composed of a predefined number of the reconstructed neighboring luma samples among the plurality of reconstructed neighboring luma samples;
• identifying, from the sub-group of the plurality of reconstructed neighboring luma samples, at least one minimum luma sample, wherein the at least one minimum luma sample corresponds to a second reconstructed chroma sample of the plurality of reconstructed neighboring chroma samples;
• fitting a linear model through the at least one maximum luma sample, the at least one minimum luma sample, the first reconstructed chroma sample, and the second reconstructed chroma sample;
• predicting chroma samples of the chroma block by applying the linear model to the luma samples of the luma block;
• and
• reconstructing the chroma block based on the predicted chroma samples.