Screen content coding for HEVC using edge modes

In this work, a new coding tool called Edge Mode is proposed for HEVC intra coding, aimed at improving coding efficiency for screen content video. A set of edge modes that correspond to edge positions are identified based upon intra prediction directions. Then, a simplified scheme is developed to select the best edge mode. To avoid applying a transform over strong edges, directional 2D separable transforms are applied to blocks partitioned using these edge modes. Experimental results show that HEVC with edge modes (HEVC/EM) can achieve up to an 18% reduction in bit-rate as compared to unmodified HEVC, with an average reduction of 10.4% for screen content video sequences.