2-D Index Map Coding for HEVC Screen Content Compression

This paper introduces a 2-D index map coding of the palette mode in screen content coding extension of the High-Efficiency Video Coding (HEVC SCC) standard to further improve the compression performance. In contrast to the current 1-D search using RUN to represent the length of matched string, we bring the block width and height to describe the arbitrary rectangle shape. We also use the block vector displacement to signal the matched block distance efficiently. By enlarging the search range from current coding tree unit (CTU) to a small neighbor CTU window (i.e., 3×5 CTUs), it provides the coding efficiency comparable to the case that full-frame intra block copy is used. It is more practical to use the local search window in real life considering the trade-off between the coding efficiency and implementation cost.