What’s the difference between HDR10, HDR-1000, and DisplayHDR 1000?
Often, we see the question of how to compare HDR10 and DisplayHDR. Which is better, and why? The answer in this case is very easy: DisplayHDR is better, but this is a little tongue-in-cheek because they aren’t really the same thing. DisplayHDR is a performance spec that measures different aspects of HDR quality, including luminance, color gamut, bit depth and rise time. HDR10, on the other hand, is a protocol, which is how HDR data is represented in a format that is understood by the GPU and the display. Other protocols you may have heard of are HDR10+, DolbyVision, and Hybrid Log Gamma (HLG). If you really wanted to compare HDR10 with the alternatives then it should be compared with these three other protocols for HDR. However, to make this very simple, HDR10 is the de-facto standard used by all HDR devices. Many devices support more than one protocol, but more than 99% of devices support HDR10 – so this is the protocol that provides the most extensive interoperability with other devices. Windows only supports HDR10 for the output from a GPU to an external display.
While HDR10 is a protocol, and DisplayHDR is a performance spec, one of the fundamental requirements of a DisplayHDR certified device is that it supports the HDR10 protocol as a foundational minimum requirement. Hence, it’s fair and accurate to say that DisplayHDR is better than HDR10, because it includes HDR10 and then adds further requirements beyond that!
The next question, or confusion, that we often see is when people compare HDR-600 and DisplayHDR 600, or HDR-1000 and DisplayHDR 1000. Are these the same thing? The answer is no, and this time not because one is a protocol and the other a performance spec (both are in fact performance specs). However, HDR-600 and HDR-1000 are undefined specs. What does that actually mean?
One might assume that HDR-600 means that a display would be able to handle an HDR signal and some part of the screen would be able to achieve 600 cd/m2 luminance levels. However, do you know how much of the screen? Do you know the test patterns? Do you know how long the display is required to display at this level before power or thermal regulation kicks in and reduces the luminance level? No, you don’t. No one does. HDR-600 and HDR-1000 are undefined specs. Nothing about the testing methodology is disclosed, and so it’s impossible to really know what they mean. Further, do they indicate the color gamut coverage, or the black level of the HDR dimming, the speed of response time for the HDR dimming, or the accuracy of the luminance and color output from the display? Again, the answer is no – there is no definition at all.
This is the huge advantage of the DisplayHDR logo, which VESA has spent three years developing in collaboration with all the major players in the PC display ecosystem. On the DisplayHDR website (www.displayhdr.org), we clearly define every test specification that is required for devices to be certified. As examples of the comparison with the undefined HDR-1000, DisplayHDR 1000 defines what the test pattern is, how long the test pattern is to be tested, and how frequently the test pattern is tested. We even specify the ambient temperature of the test environment, and the required accuracy of the test tools. This ensures that when you buy a device with DisplayHDR 1000 certification, you know what you’re buying. Furthermore, the logo’s scope is significantly broader than merely a peak luminance patch test. We also apply rigorous full-screen flash tests, and full-screen long duration tests, color tests using the exact color primary data from the Extended Display Identification Data (EDID), i.e. exactly how Windows will use the display, rather than by using arbitrary signal test color data that won’t accurately represent how Windows would ever use the display. With the latest version of the DisplayHDR spec, CTS v1.1, we also test that the HDR dimming works dynamically to ensure that it’s not just a super bright 1000 cd/m2 SDR display, but rather that it genuinely behaves as an HDR display using active dimming while the video signal luminance levels fluctuate in normal usage. A summary list of all of the tests that must be passed is available on the DisplayHDR website. All of these performance criteria are stated as minimum requirements for the logo, in that every performance criterion needs to be met by certified displays.
Furthermore, what makes DisplayHDR truly unique is that not only do we provide open access to the full 80-page certification test specification document that details every test case, but we also provide open access to an automated test tool that can be used to dynamically create all the appropriate test patterns, and test images, for each and every display based on input from the display’s own EDID block. To make the process even more comprehensive, we provide an Excel-based data recording template for you to enter the results you record during the testing process, and this Excel template will indicate pass or fail status. Finally, if you want to take it even further, we also provide open access to the test tool’s source code.
Hopefully this makes the situation clear. Not all HDR is created equally. Look for the DisplayHDR logo, because if the logo’s missing, there’s probably a good reason why.