Improvement of Implicit Residual DPCM for HEVC

For exploiting the spatial redundancy in intra coded coding unit (CU), a block-based angular intra prediction is defined in high efficiency video coding (HEVC). In lossless coding condition without transform, quantization, and in-loop filter, pixel wise differential pulse code modulation (DPCM) achieves better coding improvement than block-based prediction since it is possible to make intra prediction pixels from adjacent neighboring pixels. In HEVC Range Extension (RExt) that was finalized recently, residual DPCM (RDPCM) to use pixel wise DPCM was included. In the paper, we propose an improved RDPCM by applying an additional prediction on the residuals obtained after RDPCM. Experimental results show that the saving bits of the proposed method is 7.29% on average compared to HEVC lossless intra coding. When the proposed method compare with RDPCM, the extra saving bits of 1.46% is achieved.