With HDR (High Dynamic Range) video sources and HDR-capable projectors now both available, it is certain that HDR and UHD resolution can take picture quality up a significant step. However, at the moment HDR is very much bleeding edge, and compatibility problems between sources and displays abound. The industry will eventually work out the kinks, and everything will work together seamlessly without you having to know any details. For now, however, here are some tips on how to navigate the HDR landscape.
First, let's look at important HDR standards, specifications, and guidelines:
The oversimplification you'll see most often is that there are two HDR standards that you need to match between the video source and display--HDR10 and Dolby Vision--with the assumption that if both support the same one, they'll work together. The reality is that:
1. Dolby Vision, once again, is irrelevant for projectors. There are no models currently supporting it or on the near horizon, and
2. Just because a video source and projector both support HDR10 doesn't mean they'll work together to give you an HDR image. In theory you should be able to predict whether they'll work together based on the signal formats they support. In practice, it helps to have hands-on testing to confirm compatibility, or to get confirmation from authorized resellers.
With that in mind, we've compiled results of compatibility testing reported by all three vendors currently selling HDR-capable projectors that support UHD input and offer either native 4K resolution or 4K-emulation (what JVC calls e-shift and Epson calls 4K enhancement Technology). The test results are on the next page.
HDR Color definitions
Color depth: Also known as bit depth, color depth refers to the number of bits used to define the levels of each of the three color components, Red, Green, and Blue, in a pixel. 8-bit color is common. This is also confusingly referred to as 24-bit color because a pixel is defined by three color components. (8 bits per color times 3 colors equals 24 bits per pixel). A little arithmetic will reveal that 2 to the 8th power gives you 256 different potential values for each R, G, and B component, and 256 x 256 x 256 gives you the 16.7 million colors you hear advertised all the time. So 8-bit color depth equals 16.7 million colors.
We now have the option for deeper color systems using 10-bits or 12-bits per color. By the same logic, these can also be referred to as 30-bits and 36-bits per pixel.
HDR10 color depth: The HDR10 definition specifies 10 bits per color. Some HDR10-compatible devices also support 12 bits per color, which HDMI 2.0 and 2.0a (which adds HDR support) have the bandwidth to handle. However, 12-bit color isn't part of the HDR10 definition.
What HDR? Get a dark room. With projectors, HDR of any variety works best when viewing at night or in a dark room. HDR can give you blacker blacks and more brilliant highlights than SDR for a wider tonal range. However, to see the difference on a projector you must be viewing in a very dark room. Even a small amount of ambient or reflected light will compromise black levels, reduce contrast ratio, and hide much of the difference between HDR and SDR. It doesn't take much light to do that, so to get the full visual benefit, you'll want the viewing space as close to a black hole as possible.
As with any newl standards, manufacturers can interpret the details of HDR10 differently. This can lead to outright incompatibilities between products or just make it a little harder to get them working together than it should be. Fortunately, there are only a handful of HDR-capable projectors, UHD Blu-ray players, and game consoles available--or soon to be available--at this writing, which makes it easy to compile a list of what works with what. The information presented here is based on testing results reported by Epson, JVC, and Sony.
One type of HDR source material that has not been thoroughly tested is streaming video from Netflix, Amazon, and Sony Ultra, all of which support HDR10 with UHD. (VUDU limits itself to Dolby Vision only). The problem is that 4K HDR compatibility testing with streaming sources is complicated by the extra hardware that connects the source to the projector. A projector might show a 4K HDR signal from Netflix through one device but not through another. So compatibility testing with streaming sources is a lot more complicated than testing with Blu-ray players or game consoles that interface directly to the projector. In short, if 4K HDR is on the bleeding edge, streaming 4K HDR is on the leading edge of the bleeding edge.
The HDR projectors covered in this overview are:
Epson HDR Models:Home Cinema 5040UB
Home Cinema 5040UBe
JVC HDR Models:DLA-RS400
Sony HDR Models:VPL-VW5000ES
All of the native 4K or 4K enabled projectors above are compatible with 4K standard dynamic range (SDR) signals. It is when you go to 4K HDR that it gets dicey. The following 4K HDR source devices have compatibility with the projectors listed above as follows:
MS XBOX ONE S:
Match Specifications to Determine HDR Compatibility
It is possible to research specs and try to make sure the source device and projector match in order to determine compatibility. Most buyers won't want to do this. The easiest way to deal with this will be to ask a professional authorized reseller for the latest info. They are likely to have the most updated information about specific compatibility for either the devices above, new source players that will be coming onto the market in the future, or compatibility with streaming sources.
If you want to attempt it yourself and the combination of projector and video source you're considering isn't on the previous page, you can still tell whether they should work together for 4K HDR--or 4K SDR--by looking at the specifications for each. First, for HDR to work, they both have to be HDR10 compatible. Beyond that, they need to both support the same chroma subsampling levels at the frame rate and resolution you need.
The resolution in this case is 4K. The two frame rates that matter are 24p, for UHD Blu-ray discs, and 60p, if you're interested in 4K HDR games.
The color depth can be 8-bit, 10-bit, or 12-bit, with 10-bit the only choice that's actually defined by HDR10.
You don't need to know what the subsampling levels mean. Just note that the choices are identified as 4:4:4, 4:2:2, and 4:2:0. You need at least one of those supported by both products at the resolution (4K), frame rate (24p, 60p, or both), and color depth (10- or 12-bit for HDR) that you plan to use.
One thing to watch out for: The ability to support any combination of resolution, frame rate, color depth, and chroma subsampling level is basically a bandwidth issue, with higher levels of each adding more bits of data that requires more powerful chipsets that can handle the additional workload. So you would expect a projector that can handle a high bandwidth combination would also be able to handle any combination that's less demanding. However that's not necessarily true. Make sure that both the projector and potential video source specifically say they support HDR with at least one combination that matches.
Some Troubleshooting Tips
If you've confirmed that your projector and video source are compatible according to the manufacturer's test results or by matching specifications, but you're still not getting a 4K HDR image--or aren't sure if you are--here are some troubleshooting steps to try.
Make sure all of your devices are updated with the latest firmware.
Check to see if the projector recognizes the input as 4K HDR:
If your projector is indicating that it is receiving 4K HDR input and you don't see the effect, try making the room as dark as possible. Keep in mind that ambient light will wash out dark areas to reduce contrast ratio and hide much of HDR's advantage.
If your hardware has more than one HDMI port and they're not all HDMI 2.0a, make sure the cable is connected to an HDMI 2.0a port.
Make sure your HDMI cable can handle the bandwidth. Most standard HDMI cables are not UHD certified.
Make sure you're following the projector manufacturer's setting recommendations, if any, for HDR content.
Epson offers a FAQ here.
In addition, Epson recommends using the Bright Cinema setting for HDR content in most lighting conditions. It also says that with the current firmware at this writing, and the default setting of Auto for Dynamic Range, the projector uses its HDR 2 mode with HDR input. However, you should also experiment with manually changing the setting to HDR 1, HDR 3, and HDR 4. To change the setting, choose Signal, Advanced, Dynamic range, and then pick the setting you want.
HDR 2 is the default because Epson considers it the choice most people will prefer with most lighting conditions. HDR 1 gives a brighter image, which you might prefer in a room with more ambient light. HDR 3 and 4 give a darker image, which might be your preference in darker rooms. Of the four choices, HDR 4 is actually closest to the HDR10 specification according to Epson, but in our experience it is too dark even in a dark room with a small screen.
The disadvantage of setting HDR to one of its alternative modes with Epson's current firmware is that the projectors will then use that mode for all input signals, including SDR content, which messes up SDR image color and contrast. To avoid that happening, you need to manually switch the Dynamic Range setting back and forth between Auto and HDR 1, 3, or 4 as needed. Epson is also planning a firmware update that will let you change the HDR mode for the Auto setting to be any of the HDR modes. Once you change the HDR setting for Auto to user, you won't need to change the Dynamic Range setting manually when switching between HDR and SDR input.
JVC's recommendations are available here.
Sony doesn't have instructions online, but says their projectors need HDR set to Auto (the preferred setting) or On. With the latest firmware for all Sony projectors at this writing, the projector will detect the color space actually being used. If it detects BT.2020 in the data stream (as distinct from what the header says), it will automatically switch to it with no option to change the Color Space setting. Otherwise, it will use the current setting for Color Space, but you can manually change it by going to the Picture Menu, choosing Expert Setting, and then Color Space.
Sony says this is needed to give you better color quality with early HDR discs, many of which include a header indicating that they're using BT.2020 but were created from files using Rec.709 without adjusting the color values. The new firmware also lets you change the average picture brightness when viewing HDR content. You can adjust it to taste with the HDR Contrast setting in the Picture Menu.