Cross component decorrelation for HEVC range extension standard

This paper presents a new coding tool named cross component decorrelation in the emerging High Efficiency Video Coding Range Extension (HEVC RExt) standard. Color video is generally composed of three color components, e.g., RGB or YCbCr. It has been known for over a decade that the three color components have correlation among each other. Although global out-of-loop color space conversion, e.g., RGB-to-YCbCr, can reduce the cross component correlation, local correlation still exists in YCbCr signal. Many methods have been developed in the literature to exploit such redundancy to improve coding efficiency. However, existing methods introduce high computational or implementation complexity, which makes them never be included in mainstream video coding standard such as H.264/AVC and HEVC version 1. In this research, a new hardware friendly cross component decorrelation method is presented which reduces implementation cost while achieving significant BD-rate reduction. For example, based on JCT-VC common test condition for HEVC RExt standardization, the proposed method results in (17.3%, 18.1%, 16.6%) BD-rate reduction for the three color components of the RGB test sequences, in the case of All Intra configuration.