When Disparity meets Distance: HEVC Compression of Double-Faced Depth Map

A depth map is inherently double-faced, one single depth map can provide two closely related 3D-vision parameters (i.e. the disparity s and the distance z). Most existing depth map compression techniques considered only one of them at a time, rather than addressing the effect of compression for the two parameters simultaneously. In order to remedy this shortage, a new distortion function is proposed and integrated into HEVC 3D compression framework to examine the effectiveness with respect to s and z at the same time. Experimental results show that, with the aid of the proposed distortion function, the rate-distortion performance of the distance quality will be significantly enhanced (from 0.5 dB to 8 dB), while keeping the corresponding quality of disparity almost the same. In addition to the coding performance improvements, we also discovered some interesting phenomenons that never occurred in traditional compression framework. We expect this work can inspire more interesting research works on depth map compression.