Gamut Rings Extension for HDR Evaluation

This discussion focuses on a new method for visualizing High Dynamic Range (HDR) color performance using an expanded version of Gamut Rings.

Limitation of Standard Charts: Jeff Yurek explains that traditional CIE 1931 chromaticity diagrams are insufficient because they lack luminance data, meaning they don’t represent the full “color story.”
Gamut Rings Explained: Traditional Gamut Rings use 10 rings to represent color volume across L* steps (0–100), but this scale is designed for SDR signals.
The HDR Innovation: To map BT.2020 content, Jeff introduces three new outer rings that extend beyond the standard scale:
- 500 nits for increased brightness.
- 750 nits specifically for specular highlights.
- 4,000 nits for high-end signal extensions.
Standardization Efforts: Cinematographer Florian Friedrich is working with Masaoka-san (the original pioneer of gamut rings) to standardize this expanded model within international organizations.
Practical Value: This approach allows for a “perceptually accurate” analysis of how modern displays handle the extreme brightness and color saturation found in HDR video.