# A Display-Adaptive Pipeline for Dynamic Range Expansion of Standard Dynamic Range Video Content
## 4 Results and Evaluation
### Ldr-to-Hdr Conversion: Subjective Evaluation
For each trial in our experiment, participants were shown a pair of video sequences side by side: one representing the original LDR version and the other its HDR counterpart computed by our pipeline. These pairs were randomly arranged on the left half and right half of the screen. Participants, seated 1.5 m away from the screen, were assigned the task of judging which video, left (Video 1) or right (Video 2), showed superior quality. The criteria for \"superior quality\" were defined by how closely the video resembled a natural scene and the minimal presence of artifacts. Participants could also indicate if they perceived both videos to have equal quality. This setup was intended to ensure an unbiased evaluation as the participants were not informed which video was the LDR version and which was the HDR version obtained using our pipeline. Twenty-four short video sequences, each approximately 10 s in duration with a wide range of contrast and lighting conditions, were used in our subject study. These video  
Figure 12: The setup used for the evaluation of the proposed pipeline. The LDR and inverse tone-mapped HDR video sequences were randomly placed on the left (video 1) and on the right (video 2) on the HDR screen in each trial. LDR video sequences were linearized and adjusted to simulate the same appearance when it is displayed on an LDR screen with a limited peak brightness of 250 cd/m\({}^{2}\). sequences were obtained from publicly available video documentaries and trailers in LDR with a resolution of \(1920\times 1080\) pixels and at 24 fps. We converted all the video sequences to HDR offline to prevent any delay when displaying the video sequences: delays could affect the quality of the video; therefore, the reliability of the experiment will be altered. The HDR frames were encoded and stored in a format that SIM2 uses to display linear HDR content. Figure 13 shows a preview of some of the video sequences used in our experiments. Eight non-expert participants, aged between 17 and 42 with normal or corrected vision, took part in our subjective experiment. None had significant experience in professional video editing or color grading, ensuring the focus was on a general viewer's perspective rather than a technical one. This age range was chosen to encompass a broad spectrum of perspectives, from younger participants who might be more tech-savvy to older participants with more traditional viewing habits. Aware of the potential biases introduced by participant characteristics and experimental setup, measures were taken to mitigate these effects. The age range of participants was aimed at encompassing diverse preferences, and the inclusion of non-experts was aimed at capturing perspectives representative of a wider audience. The experiment enforced standardized viewing conditions in a dimly lit room for consistent visual environments. Stimuli were randomized among participants, and scenes were diversified in source and context. To prevent fatigue, the experiment was divided into two sessions. The results of our subjective assessment, as illustrated in Figure 14, reveal a noteworthy trend in participants' evaluations. Evidently, the HDR video sequences generated with our pipeline consistently garnered higher quality judgments compared to their corresponding LDR counterparts. This preference was particularly pronounced in scenes characterized by vibrant and high-contrast visuals featuring striking bright highlights. Participants  
Figure 13: Preview of some video sequences employed in our LDR-to-HDR conversion evaluation experiment sourced from publicly accessible video documentaries and trailers. All video sequences have a resolution of \(1920\times 1080\) pixels and 24 fps. (The original producers of the video sequences retain all rights pertaining to the frames shown in this figure). consistently leaned towards HDR content in these scenarios, highlighting a preference for its enhanced visual richness and dynamic range.