Abstract
An efficient down/upsampling method to compress a depth map efficiently within the high-efficiency video coding (HEVC) framework is presented. A different edge-preserving depth upsampling method is proposed by using both the texture and depth information. We take into account the edge similarity between depth maps and their corresponding texture images as well as the structural similarity among depth maps to build a weight model. Based on the weight model, the optimal minimum mean square error upsampling coefficients are estimated from the local covariance coefficients of the downsampled depth map. The upsampling filter is combined with HEVC to increase coding efficiency. The objective results demonstrate that we achieve a maximum bit rate saving of 32.2% compared to full resolution method and 27.6% compared to a competing depth down/upsampling method on depth bit rate. The subjective evaluation showed that our proposed method achieves better quality in synthesized views than existing methods do.
Highlights
The research and development in three-dimensional (3-D) video are capturing the attention of the research community, application developers, and the game industry
Aiming to take advantage of the geometric similarity within depth maps as well as the photometric similarity between the depth map and its corresponding texture sequence, we propose to use the pixel distance, intensity difference, and texture similarity to build a weight model with pn pcn þ pdn 3 þ ptn where pcn depends on the distance between the current pixel position ðxn; ynÞ and the center pixel position ðxc; ycÞ, which is measured by the Euclidean distance as Downloaded From: https://www.spiedigitallibrary.org/journals/Optical-Engineering on 02 Nov 2021 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi distðnÞ 1⁄4 ðxc − xnÞ2 þ ðyc − ynÞ2; (10)
For each reference depth map, we downsample it by a factor of two before encoding using the 3-D-high-efficiency video coding (HEVC) test model (HTM) version 4.128 with quantization parameters (QP) 24, 28, 32, 40, and 44
Summary
The research and development in three-dimensional (3-D) video are capturing the attention of the research community, application developers, and the game industry. Many interesting applications of 3-D video—such as 3-D television (3DTV), free-viewpoint television, 3-D cinema, gesture recognition systems, and other consumer electronics products— have been developed. MVD results in a vast amount of data to be stored or transmitted, and efficient compression techniques for MVD are vital for achieving high 3-D visual experience with constrained bandwidth. The introduction of MVD format allows generating an arbitrary number of intermediate views with lowcost depth image–based rendering[2] techniques, but the quality depends on the accuracy of the depth maps.[3,4] in this article, we concentrate on the compression of depth information in an MVD format
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