Performance enhancement of HEVC lossless mode using sample-based angular and planar predictions

High-efficiency video coding (HEVC) is the state-of-the-art video compression standard designed to handle the storage and transmission requirements of next-generation multimedia services. In the lossless mode HEVC, prevailing sample-based prediction algorithms in the literature have shown better prediction accuracy compared to the conventional block-based prediction within the HEVC anchor. This work proposes a sample-based prediction technique to modify the planar prediction mode of HEVC and a complete sample-based predictive encoder for the lossless mode of HEVC. In this work, we propose gradient adaptive sample-based intraprediction (GASP) as a replacement for the block-based planar prediction in HEVC. To obtain the benefits of sample-based prediction methods in both angular and planar prediction modes, we also propose a combination of ISAP, a sample-based angular prediction in the literature, with the newly proposed GASP (CIG). The experimental results demonstrate the superiority of GASP and CIG over other state-of-the-art sample-based prediction strategies in angular and planar prediction modes.