Reducing Wedgelet Lookup Table Size with Down-Sampling for Depth Map Coding in 3D-HEVC

In 3D-HEVC, a new coding standard of 3D video, Explicit Wedgelet mode within Depth Modelling Modes (DMM) partitions a depth block into two non-rectangular regions using a Wedgelet pattern selected from a Wedgelet lookup table. The Wedgelet lookup table is constructed during both encoder and decoder initialization for each block size ranging from 4x4 to 16x16, while the Wedgelet lookup table consists of a large number of Wedgelet bi-patterns, which involves relatively high computational complexity and may cause cache storing problem. In this paper, we propose a down-sampling method to reduce the number of Wedgelet patterns in the Wedgelet lookup table. The experimental results show our proposed down-sampling method can achieve storage size reduction by 27.8% with negligible 0.03% and 0.05% coding loss in both configurations of Common Test Conditions (CTC) and All Intra (AI), respectively.