DisplayHDR Spec Helps Clarify HDR Performance Levels
VESA Certified DisplayHDR brand logo representing the entry level of HDR system performance for PC displays.
The Video Electronics Standards Association (VESA) revealed Monday what it is calling the industry’s “first fully open standard specifying high dynamic range (HDR) quality, including luminance, color gamut, bit depth and rise time, through the release of a test specification.”
The new VESA High-Performance Monitor and Display Compliance Test Specification (DisplayHDR) is initially positioned at laptop and desktop PC displays and monitors that use liquid crystal display (LCD) panels.
The first release of the specification, which is called DisplayHDR version 1.0, establishes three distinct levels of HDR system performance to facilitate adoption of HDR in the PC market.
HDR provides better contrast and color accuracy as well as more vibrant colors compared to Standard Dynamic Range (SDR) displays, and is gaining interest for a wide range of applications, including movie viewing, gaming, and creation of photo and video content.
Read more about the VESA DisplayHDR test specification after the jump:
The VESA DisplayHDR specification was developed through the collaboration of “more than two dozen active member companies,” including original equipment manufacturers (OEMs) of displays, graphic cards, CPUs, panels, display drivers and other components, and color calibration providers.
The initial spec targets LCD displays, which represent some 99 percent of the PD display market, but VESA said in a statement that it anticipates future releases to address organic light emitting diode (OLED) and other display technologies as they become more common.
The specifications are also intended to address the addition of higher levels of HDR performance over time.
VESA said that DisplayHDR was developed for the needs of the PC market, but the spec could serve to address “new levels of HDR performance in other markets as well.”
VESA plans to clear up confusion over various levels of HDR performance through the use of new HDR logos and tradenames that will be open “with a fully transparent testing methodology.”
Since HDR performance details are typically not provided, consumers are unable to obtain meaningful performance information. With DisplayHDR, VESA aims to alleviate this problem by:
- Creating a specification, initially for the PC industry, that will be shared publicly and transparently;
- Developing an automated testing tool that end users can download to perform their own testing if desire;
- Delivering a robust set of test metrics for HDR that clearly articulate the performance level of the device being purchased.
As it stands, the specification establishes three HDR performance levels for PC displays:
Baseline (DisplayHDR 400)
First genuine entry point for HDR. Significant step up from SDR baseline:
- True 8-bit image quality – on par with top 15% of PC displays today
- Global dimming – improves dynamic contrast ratio
- Peak luminance of 400 cd/m2 – up to 50% higher than typical SDR
- Minimum requirements for color gamut and contrast exceed SDR
Mid-range (DisplayHDR 600)
Targets professional/enthusiast-level laptops and high-performance monitors. True high-contrast HDR with notable specular highlights:
- Peak luminance of 600 cd/m2 – double that of typical displays
- Full-screen flash requirement renders realistic effects in gaming and movies.
- Real-time contrast ratios with local dimming – yields impressive highlights and deep blacks.
- Visible increase in color gamut compared to already improved DisplayHDR 400.
- Requires 10-bit image processing.
High-end (DisplayHDR 1000)
Targets professional/enthusiast/content-creator PC monitors.
- Outstanding local-dimming, high-contrast HDR with advanced specular highlights:
- Peak luminance of 1000 cd/m2 requirement – more than 3x that of typical displays
- Full-screen flash requirement, delivers ultra-realistic effects for gaming.
- Unprecedented long duration, high performance ideal for content creation.
- Local dimming yields 2x contrast increase over DisplayHDR 600
- Significantly visible increase in color gamut compared to DisplayHDR 400.
- Requires 10-bit image processing
Eight specific parameter requirements and associated tests are applied to the differet levels. These parameters include:
- Three peak luminance tests involving different scenarios – small spot/high luminance, brief period full-screen flash luminance, and optimized use in bright environments (e.g., outside daylight or bright office lighting).
- Two contrast measurement tests – one for native panel contrast and one for local dimming.
- Color testing of both the BT.709 and DCI-P3 color gamuts.
- Bit-depth requirement tests – these stipulate a minimum bit depth and include a simple visual test for end users to confirm results.
- HDR response performance test – sets performance criteria for backlight responsiveness ideal for gaming and rapid action in movies by analyzing the speed at which the backlight can respond to changes in luminance levels.
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The spec establishes 400 nits of peak luminance as the minimum threshold for HDR in the Display400 level.
According to Roland Wooster, VESA DisplayHDR task group chairman and Intel representative, this level was selected because “400 nits is 50 percent brighter than typical SDR laptop displays. The bit depth requirement is true 8-bit, whereas the vast majority of SDR panels are only 6-bit with dithering to simulate 8-bit video.”
The DisplayHDR 400 spec also requires HDR10 support and global dimming at a minimum.
“With this tiered specification, ranging from baseline to high-end HDR performance levels, PC makers will finally have consistent, measurable HDR performance parameters,” Wooster said. “Also, when buying a new PC, consumers will be able to view an HDR rating number that is meaningful and will reflect actual performance.”
Bill Lempesis, VESA executive director said “We are the first standards body to develop a publicly available test tool for HDR qualification, utilizing a methodology for the above-mentioned tests that end users can apply without having to invest in costly lab hardware. Most of the tests require only a colorimeter, which many users already own. Ease of testing was a must-have requirement in order to make DisplayHDR a truly viable, consumer-friendly spec.”
The DisplayHDR spec comes just about a week after the HDMI Forum released specifications for HDMI 2.1, which is the next version of the High Definition Multimedia Interface intended to deliver greater bandwidth and interoperability with next generation 4K, 8K and 10K television displays and monitors. That spec is also intended to handle various levels of HDR, but doesn’t at this point list characteristics of various HDR performance levels.
The Ultra HD Alliance has also issued criteria for Ultra HD Premium level performance of 4K television displays, Ultra HD Blu-ray players and other devices, but has not addressed levels of HDR for mid- or entry range 4K/HDR televisions and monitors.
By Greg Tarr
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