Study of 3D Video Compression Using Nonlinear Depth Representation

The extensions of Advanced Video Coding (AVC) and High-Efficiency Video Coding (HEVC) for multiview video plus depth allow for the coding of 3D video scenes. During the standardization of these extensions, it was demonstrated that compression performance can often be improved by the application of nonlinear depth transformation prior to the compression and applying the respective backward nonlinear depth transformation after decompression. Such an approach is referred to as the compression of nonlinear depth representation (NDR). In this paper, a survey of the NDR technology is provided, but a large part of this survey comprises yet unpublished results. First, the motivation and rationale behind the idea of NDR are discussed. The options for the choice of nonlinear transformation are provided with the respective formulations. Also, the standardization of 3D video coding with NDR within ISO/IEC and ITU is discussed along with the experimental results that demonstrate benefits related to the application of NDR in 3D-AVC and 3D-HEVC. Furthermore, the experimental comparisons are provided for simulcast coding of multiview plus depth video using AVC and HEVC technology with and without the NDR. The similar experimental results are also provided for simulcast coding using the current version of Versatile Video Coding technology that is under development for the forthcoming standard of ISO/IEC (MPEG-I) and ITU. All of the experimental results have been obtained for the standard JVC-3V video test sequences under common test conditions for 3D video coding.