Explicit residual DPCM for screen contents coding

In this paper, we propose an explicit signaling of RDPCM scheme for a lossy intra-coded block, and achieve a significant coding gain over the HEVC Range Extension reference software in the screen contents coding. We define three RDPCM modes, and transmit the side information so that the best RDPCM mode can be applied to residual signals after all available angular directional predictions. Contexts for a CABAC coding is also designed for coding the overheads.