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Improvements of HEVC SCC Palette Mode and Intra Block Copy

Palette mode and intra block copy are two new coding tools that have been adopted in the screen content coding extensions of high efficiency video Ccoding (HEVC SCC). Palette mode can represent color clusters for screen content efficiently. Intra block copy (IBC) facilitates block prediction within the same frame. Both tools have demonstrated promising benefits for screen content coding. In addition to HEVC SCC, this paper introduces five new coding techniques to enhance palette mode or IBC: transition copy, prediction across coding unit boundary, advanced motion vector coding, modified temporal merge candidate derivation, and new default IBC merge candidates. Experimental results show that the proposed techniques can achieve 5.4%, 5.2%, and 4.9% BD-rate savings compared with HEVC SCC for “YUV, text & graphics with motion, 1080p & 720p sequences” under all intra, random access, and low-delay B common test conditions, respectively.