Hybrid log-gamma transfer function (HLG)

The hybrid log-gamma transfer function is a transfer-function that allows HDR content to be displayed on modern displays. The HLG transfer-function is compatible with the gamma function used by SDR.As the name implies, it is a hybrid function that uses the traditional gamma function for the lower part of the signal range, and a logarithmic function for the upper part. As a result, HLG content can be correctly displayed by SDR displays, as long as they support the Rec. 2020 color space. It also does not require additional metadata.