目的 新一代3D视频采用了多视点加深度图像的格式,其编码测试模型3D-HEVC(3D高效视频编码)为深度图像引入了一些新的编码技术,包括深度模型模式、分段直流(DC)残差编码模式和帧内跳过模式等,但是同时也显著地增加了帧内编码器的复杂度,严重制约了3D视频的实时应用,因此本文提出了一种深度图像帧内模式选择方法。方法 首先,分析在分层编码结构中,父层帧内模式和子层帧内模式的关系,并依据父层的帧内模式对子层的候选模式进行修剪;其次,通过分析粗略候选帧内模式,把当前块分为平滑块、方向块和边界块,并根据不同块进行候选帧内模式的选择。结果 与高效3D视频编码标准的测试模型相比,本文的深度图像帧内模式选择方法可以节省约44%的编码时间。本文方法有效地减少了计算率失真代价的候选帧内模式数目,从而降低了帧内编码器的复杂度。结论 该方法能在保证虚拟视点质量的前提下,有效地降低深度图像帧内编码的复杂度。

Objective The new generation 3D video adopts multi-view video plus depth as the main format. To improve the coding performance and quality of synthesized views, several new techniques, including depth modeling mode, segment-wise DC coding, and skip intra mode, are introduced into the current 3D-HEVC test model for depth intra coding. However, these tools dramatically increase computational complexity, which obstructs the practical applications for the 3D video. Thus, in this study, a fast depth intra coding algorithm is proposed to alleviate the burden of the encoder. Method Considering that 3D-HEVC reuses the well-known hierarchical coding structure, the mode information of the parent coding units (CU) can be reused to predict the most probable modes for the current CU. Consequently, only a subset of the intra mode candidates is employed to calculate the rough rate-distortion cost. According to rough modes and their rough costs by rough mode decision, the current CU will be classified into three categories, namely, smooth, directional, and edge. For each class, a different set of rough mode candidates will be selected. Result Simulation results show that the proposed algorithm achieves a reduction of 44% encoding time for depth intra coding while maintaining the quality of synthesized views, compared with the original test model HTM-13.0. Conclusion Based on the mode information of parent CU and rough mode decision, the proposed method can significantly reduce the number of intra mode candidates. Consequently, the proposed method can provide a remarkable time reduction of depth intra coding with a negligible BD rate increase.