Comparing common still image quality metrics in recent High Dynamic Range (HDR) and Wide Color Gamut (WCG) representations

Abstract

There are an increasing number of databases describing subjective quality responses for HDR (high dynamic range) imagery with various distortions. The dominant distortions across the databases are those that arise from video compression, which are primarily perceived as achromatic, but there are some chromatic distortions due to 422 and other chromatic sub-sampling. Tone mapping from the source HDR levels to various levels of reduced capability SDR (standard dynamic range) are also included in these databases. While most of these distortions are achromatic, tone-mapping can cause changes in saturation and hue angle when saturated colors are in the upper hull of the of the color space. In addition, there is one database that specifically looked at color distortions in an HDR-WCG (wide color gamut) space. From these databases we can test the improvements to well-known quality metrics if they are applied in the newly developed color perceptual spaces (i.e., representations) specifically designed for HDR and WCG. We present results from testing these subjective quality databases to computed quality using the new color spaces of Jzazbz and ICTCP, as well as the commonly used SDR color space of CIELAB.