Depth No-Synthesis-Error Model for View Synthesis in 3-D Video
Currently, 3-D Video targets at the application of disparity-adjustable stereoscopic video, where view synthesis based on depth-image-based rendering (DIBR) is employed to generate virtual views. Distortions in depth information may introduce geometry changes or occlusion variations in the synthesized views. In practice, depth information is stored in 8-bit grayscale format, whereas the disparity range for a visually comfortable stereo pair is usually much less than 256 levels. Thus, several depth levels may correspond to the same integer (or sub-pixel) disparity value in the DIBR-based view synthesis such that some depth distortions may not result in geometry changes in the synthesized view. From this observation, we develop a depth no-synthesis-error (D-NOSE) model to examine the allowable depth distortions in rendering a virtual view without introducing any geometry changes. We further show that the depth distortions prescribed by the proposed D-NOSE profile also do not compromise the occlusion order in view synthesis. Therefore, a virtual view can be synthesized losslessly if depth distortions follow the D-NOSE specified thresholds. Our simulations validate the proposed D-NOSE model in lossless view synthesis and demonstrate the gain with the model in depth coding.