Objective quality analysis for free-viewpoint DIBR

Interactive free-viewpoint selection applied to a 3D multi-view video signal is an attractive feature of the rapidly developing 3DTV media. In recent years, significant research has been done on free-viewpoint rendering algorithms which mostly have similar building blocks. In this paper, we analyze the four principal building blocks of most recent rendering algorithms and their contribution to the overall rendering quality. We have discovered that the rendering quality is dominated by the first step, Warping which determines the basic quality level of the complete rendering chain. The third step, Blending, is a valuable step which further increases the rendering quality by as much as 1.4 dB while reducing the disocclusions to less than 1% of the total image. Varying the angle between the two reference cameras, we notice that the quality of each principal building block degrades with a similar rate, 0.1-0.3dB/degree for real-life sequences. While experimenting with synthetic data of higher accuracy, we conclude that for developing better free-viewpoint algorithms, it is necessary to generate depth maps with more quantization levels so that the Warping and Blending steps can further contribute to the quality enhancement.