Buying a monitor with high dynamic range capability can be confusing. In an effort to make things easier on shoppers, the Video Electronics Standards Association (VESA) is rolling out DisplayHDR, an open and three-tiered set of specifications for HDR quality. The new standard includes test specifications for luminance, color gamut, bit depth, and rise time. The body claims DisplayHDR is the first open HDR specification with a transparent test methodology. The initial version of the spec is focused on LCD panels, but future releases will also measure OLED displays. More than two dozen companies contributed to the development of the DisplayHDR standard, including AMD, Intel, Microsoft, and Nvidia.
The baseline compliance level, DisplayHDR 400, requires true 8-bit image processing, a requirement VESA says only 15% of current PC displays can meet. DisplayHDR 400 also requires compliant displays to offer global dimming, peak luminance of 400 cd/m², full-screen long-duration luminance of 320 cd/m², and coverage of at least 95% of the BT.709 color space. BT.709 is about as wide as the sRGB gamut familiar to many PC users, albeit with a different transfer function or gamma.
The intermediate DisplayHDR 600 specification comes with a more demanding set of specifications. The peak luminance requirement is ratcheted up to 600 cd/m². Sustained bright scenes must be reproduced with at least 350 cd/m² of brightness. Black-to-white luminance response must be achieved in "eight frames" or less. The DisplayHDR 600 color-reproduction spec is also more exacting than the entry-level certification. Compliant monitors must cover 99% of the BT.709 color space and 90% of the DCI-P3 space at a minimum. To achieve high contrast, the extremely dim corner luminance requirement for DisplayHDR 600—0.10 cd/m²—will require local dimming with today's LCDs, according to VESA. The standards body expects DisplayHDR 600 screens to show up in professional and enthusiast laptops and high-end monitors.
The highest tier of DisplayHDR, DisplayHDR 1000, requires a peak luminance of 1000 cd/m², sustained luminance of at least 600 cd/m², and a corner luminance requirement of 0.05 cd/m², all steps up over DisplayHDR 600 displays. VESA says DisplayHDR 1000 was created with professional and enthusiast content creators in mind. The color space requirement is the same as that of the DisplayHDR 600 standard.
Unfortunately, VESA's DisplayHDR system of standards does not address the issue of multiple HDR content formats, but it at least lays out a simple "good, better, best" system for monitors with HDR capabilities. VESA says it will have a DisplayHDR test tool available for download before the end of the first quarter of 2018. The body says end users will be able to perform tests "without investing in costly lab hardware." A full list of performance criteria is available here.