Large-Scale Multi-Site Subjective Assessment on Image Banding Artifacts

Banding largely occurs due to the finite bit depth representation of digital media and displays. It is a unique type of artifact that is both challenging to accurately measure and difficult to properly mitigate. These artifacts can also be observed across a wide spectrum of streaming services, no matter if professional studio productions or user-generated content. Inspired by the need to monitor and measure these banding artifacts, we present a large-scale multi-site subjective study on image banding artifacts. We designed a novel two-question-based subjective evaluation protocol that goes beyond giving ratings at the frame level, but also collects subjective opinions at the sub-frame level. The high-quality subjective data are collected from a cohort of 56 participants across 3 physical sites with calibrated environments, covering diverse backgrounds and experiences. Finally, we demonstrate that none of the common banding metrics are highly correlated with the subjective data. The paper calls for a need of continued efforts in modeling the perceptual effect of banding artifacts.