Tone Mapping Operators (TMO) designed for videos can be classified into two categories. In a first approach, TMOs are temporal filtered to reduce temporal artifacts and provide a Standard Dynamic Range (SDR) content with improved temporal consistency. This however does not improve the SDR coding Rate Distortion (RD) performances. A second approach is to design the TMO with the goal of optimizing the SDR coding rate-distortion performances. This second category of methods may lead to SDR videos altering the artistic intent compared with the produced HDR content. In this paper, we combine the benefits of the two approaches by introducing new Weighted Prediction (WP) methods inside the HEVC SDR codec. As a first step, we demonstrate the interest of the WP methods compared to TMO optimized for RD performances. Then we present the newly introduced WP algorithm and WP modes. The WP algorithm consists in performing a global motion compensation between frames using an optical flow, and the new modes are based on non linear functions in contrast with the literature using only linear functions. The contribution of each novelty is studied independently and in a second time they are all put in competition to maximize the RD performances. Tests were made for HDR backward compatible compression but also for SDR compression only. In both cases, the proposed WP methods improve the RD performances while maintaining the SDR temporal coherency.

中文翻译：

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SDR和向后兼容HDR视频编码的基于光流的非线性加权预测。

专为视频设计的音调映射运算符（TMO）可以分为两类。在第一种方法中，对TMO进行时间滤波以减少时间伪像，并提供具有改进的时间一致性的标准动态范围（SDR）内容。但是，这不会提高SDR编码速率失真（RD）性能。第二种方法是设计TMO，其目的是优化SDR编码率失真性能。与产生的HDR内容相比，第二类方法可能导致SDR视频改变艺术意图。在本文中，我们通过在HEVC SDR编解码器中引入新的加权预测（WP）方法，结合了这两种方法的优点。第一步，与针对RD性能优化的TMO相比，我们展示了WP方法的兴趣。然后介绍了新引入的WP算法和WP模式。WP算法包括使用光流在帧之间执行全局运动补偿，与仅使用线性函数的文献相比，新模式基于非线性函数。每个新颖性的贡献都将被独立研究，然后第二次将它们全部竞争以最大化RD性能。对HDR向后兼容压缩进行了测试，但仅对SDR压缩进行了测试。在这两种情况下，建议的WP方法都可以在保持SDR时间一致性的同时提高RD性能。与仅使用线性函数的文献相比，新模式基于非线性函数。每个新颖性的贡献都将被独立研究，然后第二次将它们全部竞争以最大化RD性能。对HDR向后兼容压缩进行了测试，但仅对SDR压缩进行了测试。在这两种情况下，建议的WP方法都可以在保持SDR时间一致性的同时提高RD性能。与仅使用线性函数的文献相比，新模式基于非线性函数。每个新颖性的贡献都将被独立研究，然后第二次将它们全部竞争以最大化RD性能。对HDR向后兼容压缩进行了测试，但仅对SDR压缩进行了测试。在这两种情况下，建议的WP方法都可以在保持SDR时间一致性的同时提高RD性能。