Style Aware Tone Expansion for HDR Displays

Abstract

The vast majority of video content existing today is in Standard Dynamic Range (SDR) format and there is a strong interest in upscaling this content for upcoming High Dynamic Range (HDR) displays. Tone expansion or inverse tone mapping converts SDR content into HDR format using Expansion Operators (EO). In this paper, we show that current EO's do not perform as well when dealing with content of various lighting style aesthetics. In addition to this, we present a series of perceptual user studies evaluating user preference for lighting style in HDR content. This study shows that tone expansion of stylized content takes the form of gamma correction and we propose a method that adapts the gamma value to the style of the video. We validate our method through a subjective evaluation against state-of-the-art methods. Furthermore, our work has been oriented for 1000 nits HDR displays and we present a framework positioning our method in conformance with existing SDR standards and upcoming HDR TV standards.