Since 2015 video dimensionality has expanded to higher spatial and temporal resolutions and a wider colour gamut. This High Dynamic Range (HDR) content has gained traction in the consumer space as it delivers an enhanced quality of experience. At the same time, the complexity of codecs is growing. This has driven the development of tools for content-adaptive optimisation that achieve optimal rate-distortion performance for HDR video at 4K resolution. While improvements of just a few percentage points in BD-Rate (1-5\%) are significant for the streaming media industry, the impact on subjective quality has been less studied especially for HDR/AV1. In this paper, we conduct a subjective quality assessment (42 subjects) of 4K HDR content with a per-clip optimisation strategy. We correlate these subjective scores with existing popular objective metrics used in standard development and show that some perceptual metrics correlate surprisingly well even though they are not tuned for HDR. We find that the DSQCS protocol is too insensitive to categorically compare the methods but the data allows us to make recommendations about the use of experts vs non-experts in HDR studies, and explain the subjective impact of film grain in HDR content under compression.

翻译：自2015年以来，视频维度已扩展至更高的空间与时间分辨率及更广的色域。高动态范围（HDR）内容因其能带来增强的体验质量，在消费领域日益普及。与此同时，编解码器的复杂度也在不断增加。这推动了内容自适应优化工具的发展，旨在为4K分辨率下的HDR视频实现最优率失真性能。尽管BD-Rate（1-5%）仅几个百分点的提升对流媒体行业意义重大，但其对主观质量的影响却鲜有研究，尤其是在HDR/AV1场景下。本文针对采用逐片段优化策略的4K HDR内容开展了主观质量评估（42名受试者）。我们将这些主观评分与标准开发中使用的现有流行客观指标进行相关性分析，发现某些感知度量虽未针对HDR进行调优，却呈现出出人意料的良好相关性。同时，我们发现DSQCS协议对方法间的分类比较过于不敏感，但基于数据可针对HDR研究中专家与非专家的选用提出建议，并解释压缩过程中HDR内容中胶片颗粒的主观影响。