Adaptive boundary dependent transform optimization for HEVC

High Efficiency Video Coding (HEVC) adopts hybrid transform coding scheme to improve the transform performance. However, it does not consider the influence of the prediction unit boundary. This paper proposes an adaptive boundary dependent transform optimization scheme for HEVC. Based on the transform unit boundary type identification by checking whether it lies at a prediction unit boundary or not, some additional transform kernels, including DCT-IV, are incorporated for transform. Moreover, the additional adopted transform kernels are generated by re-using the existing kernels in HEVC. Therefore, the butterfly structure for transform implementation can be preserved to facilitate parallel computing, and computational complexity increasing can be avoided. Experimental results show that the coding performance improvements can be up to 0.96% and 0.64% for low delay P and random access testing configurations respectively.