High dynamic range video coding

Abstract

Methods for the efficient coding of high-dynamic range (HDR) stillimages and video sequences are reviewed. In dual-layer techniques, a base layer of standard-dynamic range data is enhanced by additional image data in an enhancement layer. The enhancement layer may be additive or multiplicative. If there is no requirement for backward compatibility, adaptive HDR-to-standard dynamic range (SDR) mapping schemes in the encoder allow for improved coding efficiency versus the backward-compatible schemes. In single-layer techniques, a base layer is complemented by metadata, such as supplementary enhancement information (SEI) data or color remapping information (CRI) data, which allow a decoder to apply special "reshaping" or inverse-mapping functions to the base layer to reconstruct an approximation of the original HDR signal. New standards for exchanging HDR signals, such as SMPTE 2084 and BT. 2100, define new mapping functions for translating linear scene light captured by a camera to video and are replacing the traditional "gamma" mapping. The effect of those transforms to existing coding standards, such as high efficiency video coding (HEVC) and beyond, are reviewed, and novel quantization and coding schemes that take these new mapping functions into consideration are also presented.