Implicit Transform Selection based on Cross Color Component Prediction for Future Video Coding

In the study of video coding technologies, Discrete Cosine Transform type II (DCT-II) has been employed for energy compaction. To improve coding efficiency, Multiple Transform Selection (MTS) scheme is recently proposed where Discrete Sine Transform type VII (DST-VII) and DCT-VIII are newly introduced with explicit signaling. MTS is not applied for chroma components due to the limitation of computation complexity at an encoder side. This paper proposes implicit transform selection to apply DST-VII for the chroma blocks based on the intra prediction mode applied to the chroma block. The experimental results show 0.45% and 0.48% BD-rate gain in all intra configuration for Cb and Cr components compared to the conventional method with negligible impact of encoding and decoding complexity.