A Single-Layer HDR Video Coding Framework with SDR Compatibility

The migration from high-definition TV to ultrahigh definition (UHD) is already underway. In addition to an increase of picture spatial resolution, UHD potentially provides more color by introducing a wider color gamut, and better contrast by moving from standard dynamic range (SDR) to high dynamic range (HDR). The transition from SDR to HDR will require distribution solutions supporting some level of SDR backward compatibility. This paper presents the HDR content distribution scheme jointly developed by Technicolor and Philips. The solution is based on a single-layer codec design and provides SDR compatibility, thanks to a preprocessing step applied prior to the encoding. The resulting SDR video can be compressed and distributed, then decoded using standard-compliant decoders (e.g., high efficiency video coding Main 10 compliant) and directly rendered on SDR displays. Dynamic metadata of limited size are used to reconstruct the HDR signal from the decoded SDR video, using a post-processing that is the functional inverse of the preprocessing. Both HDR quality and artistic intent are preserved. Pre- and postprocessing are applied independently per picture, do not involve any interpixel dependence, and are codec agnostic.