Stranger HDR Things

High Dynamic range, or HDR, is perhaps the most exciting of the trio of improvements that Ultra HD brings to the table, the others being a wider color gamut and higher resolution. The images from a flat screen set pop off the screen in a way that the dimensional but often too dim 3D never could. And you don’t need special glasses to see it.

A flat screen set, capable of peak brightness levels of over 1000 nits (just under 300 foot-lamberts) can make the most of an HDR source. HDR program material is mastered for a peak output of either 1000 nits or 4000 nits, with most of that luminance reserved for bright highlights.

But not all displays can hit 1000 nits, and we know of no consumer products capable of anything beyond 2000. And not all displays can reach even 1000 nits; OLEDs, for example, generally top out at under 700, and cheaper 4K LCD/LED designs can’t even get to that.

There’s no tone mapping standard. We can tell you that tone mapping is almost universal, but not how it’s done.

If an HDR-capable set with, say, 500 nits of available peak luminance sees a scene that peaks at 1000 nits, what does it do with it? Absent any other processing it would simply clip all of the information above 500 nits. But to preserve at least the sense of that information, the set then “tone maps” it. How is this done? That’s where the fun begins, because the actual tone mapping process is up to the TV maker. There’s no tone mapping standard. We can tell you that tone mapping is almost universal, but not how it’s done—which in any case might require a Mensa membership to fully comprehend. If all sets were limited to a fixed peak brightness of, say, 1000 nits, and all sources limited to the same 1000 nits, tone mapping would never be needed. But with the wide range of product prices and performance on the market, that was never possible. So tone-mapping is with us and likely always will be until the peak brightness of our displays matches the peak brightness that can be mastered onto the source.

But the fun doesn’t stop there. HDR in projectors adds another whole layer of complexity to the mix. In fact, HDR was developed with consumer televisions in mind, not projectors. A home theater projector is unlikely to offer a peak brightness output of more than 150 nits, though the Epson 4000 I recently reviewed topped out at a “searing” 174 nits in Bright Cinema mode. But even that’s a hair on the dog of a good flat screen set’s peak output. That means that the tone mapping on a projector needs to begin at a far lower source level, and be far more aggressive. This makes a projector far trickier to set up and optimize in HDR than a flat screen set.

Ideally we’d have special “projection only” versions of HDR releases, mastered at a peak level of 150-200 nits. But that’s not happening. And there are other variables as well with projectors, including the size and gain of the screen. The only way to standardize for that would be to specify not only the capabilities of the projector but also everything else in the system. That’s unlikely to happen either. The only place you’ll find it is in one of the Dolby Cinema theaters, with about 100 of them scattered in multiplexes around the country. Dolby Cinema is a closed system; each piece of the puzzle, from content mastering to the screen, is fixed and known. No tone mapping needed there. But in our crazy world of ad hoc home theater, there are few such standards. HDR from a projector, for now, is the Forest Gump’s Box of Chocolates of the home theater world. You never know exactly what you’re going to get…but it usually tastes good.

drny's picture

Personally I am not wowed by OLED displays. At least not at 65" size display viewed in a living room with ambient light.
The main reason is that OLED black level excellence requires a true home theater room. That is to say a dark viewing room to maximize its contrast prowess.
HDR tone mapping on an OLED display looks impressive if viewed in a darken room. But the same can be said of a JVC-DLA faux 4k projector.
Under ideal circumstances, 10 feet away from the screen the image on a 100+ projector screen will be far more impressive than the 65"OLED at the same distance. Technically the OLED is far superior in reproducing detail and contrast of the HDR tone mapping, but optically our human eye will be capture by the larger image.
You doubt my assertions.
Please go to the nearest Dolby Vision Cinema Theater and see Blade Runner 2049. It is a fantastic sensory experience.
When the UHD is release the HDR tone mapping will far exceed that of the one in the Dolby Vsion Theater. Go ahead purchase an OLED and view the same movie 7 feet away from the screen.
You will be amazed but the experience won't match the Dolby Vision theater, or that of a true 4k or very decent faux 4k home projector.

johnty's picture

Enough with the HDR is 3D comparison. "The images from a flat screen set pop off the screen in a way that the dimensional but often too dim 3D never could." Nonsense. My passive 3D LCD TV displays Dolby Vision 4K HDR which is indeed stunning. My 3D movies are only 2K and will never have HDR but, with the proper settings, are just as bright as 2D programs. They also have incredible depth and "pop off the screen" visuals that 4k HDR can only dream about.

Too many writers love to use the HDR is 3D analogy. Too many writers are wrong.

CinemaDude's picture

When I was a kid, I remember as if it were yesterday, sitting in one of Century Theatres' "Flagship" theatres in Queens NY (they were "theatres" back then, not "cinemas") an watching in absolute astonishment and awe as the curtains parted (you remember curtains in movie theatres, then I applaud your youth) and the words HOUSE OF WAX hung about three feet in front of face, so real and with such an incredible sense of depth and feeling of space, that it was like a new discovery for my eyes. The impact of that experience was monumental to a little kid already fascinated by movies. I have been in love with 3D ever since.

To me, binocular vision is no different than binaural sound. You see an 2D image, but when the second image is turned on, while you really don't see anything more in that image than you saw in the 2D version, now when your eyes can see both images, all of a sudden space between objects and the FEELING of that space instantly becomes a new and different and remarkable reality. It is sight PLUS the feeling of space. And it is a totally separate and unique physiological experience than seeing a 2D image.

I made my poor mother sit with me thru a second showing HOUSE OF WAX and then I refused to go home and she finally had enuf and told me that my dad would come by to pick me up after my third go-round. To me, this was like a new way of seeing a movie -- as impressive as color was to black and white (maybe more) and later as Cinerama was to Academy 4:3 aspect ratio. I kept pestering my dad as we drove home, talking incessantly about what I just experienced seeing HOUSE OF WAX 3D; "They are going to make ALL movies in 3D now, aren't they...the HAVE to!" All I got was, "Enough already. How do I know?" He had no idea what 3D even was.

In the late 70s I nearly went hungry so I could buy Advent's famed VideoBeam so I could have my own home theatre before anyone had invented the term Home Theatre; Watching films on its 7ft silverized screen was impressive. Imagine my delight when in the mid-80s 3DTV, a small company offered a 3D video system using SVHS tapes using alternate-frame 3D videos of a number of titles from the 50s 3D library, including low and behold, HOUSE OF WAS. I was a kid again! I was able to show that title -- my first and never forgotten 3D experience -- now come full circle, in my own living room. Hooked up to the Videobeam, this was a miracle for me, despite the fact that you needed to wear pretty clunky WIRED active shutter glasses. Hey, don't knock it -- with wired active glasses you never have to worry about BATTERIES dying in mid-movie!

What has always baffled me, is this seemingly irrational resistance to 3D -- the glasses...the glasses. You hear that over and over, as if people don't willingly and lovingly don sunglasses and wear them for hours upon hours at the beach or all day in the summer. I never hear anyone say they rather not go to the beach because they have to wear sunglasses. For me the experience of seeing -- no, the right word is FEELING -- the space between objects is so impressive that I would wear a space helmet to get it. True my 3DTVs are passive, so the glasses are no more bulky that the RealD cinema glasses (take them home -- you paid for them -- and they work perfectly on an LG passive 3D TV). And not-for-nuthn as we say in Brooklyn, an LG TV image is brighter than ANY movie theatre where I have seen 3D, with the exception of IMAX which uses dual projectors.

And then there's that odd almost absurd complain I've heard that 3D doesn't ADD anything to a movie experience; they'd be just as happy...some even claim they'd PREFER to see a 3D movie in 2D. Huh? Really? That's like saying stereo sound doesn't add anything to the music listening experience. So would they be happy or would they prefer to hear everything in mono sound? Same, exact comparison. Stereo sound adds the feeling of space in and around the instruments; it does for the ears exactly what 3D does for sight -- those two separate images or sound channels gives the brain information that allows it to FEEL SPACE. And remarkably, without drugs. Both are spectacular sensual experience for both senses. And did I mention you get it without drugs? So what's not to love? Difference is, you never hear anyone begrudging stereo sound the way you do the 3D haters -- you know the ones even in the industry who keep referring to it as a "fad." Some fad -- going on nearly 20 years since AVITAR, and nearly 70 years since HOUSE OF WAX. Sure, different versions of the technology has come and gone but the 3D experience still is a magnificent experience in both sight and sound.

Problem is, the haters seem to have gathered enough momentum that the industry has stopped manufacturing 3DTVs. When I saw this handwriting on the wall, I purchased a second LG OLED 3D TV and 3D BluRay players and all the 3D BR released I can get my hands. I want to future-proof my home theatre from a world where there is no 3D, at least not for the home. Maybe some future direct-view 3D technology (no glasses) will silence all the wimps who won't watch 3D because they have to put on a pair of glasses. Until then, you can come watch HOUSE OF WAX anytime in my house.

DavidH's picture

johnty is right. HDR and 3D are different creatures. When I first heard of 3D for the home I was a sceptic. Who would wear glasses to watch TV? But 3D on LG's OLEDs has changed my mind. This is an exceptional experience; as good (or better) than many theaters can give.

HDR, on the other hand, is a very mixed bag. Great for capture, but so-so for home displays. I have seen one or two good examples - and many bad. Wide color gamut is terrific, but who needs 1,000 nits blasting from their TV? Maybe for a tiny highlight, but not for large expanses of the screen - that is downright unpleasant. And to "show off" HDR we are being given scenes with actors sitting in front of large windows at peak brightness. Where are my sunglasses?

HDR is being sold as the next coming, but I'm not on the bandwagon.

WildGuy's picture

i didn't really know or thought about tv with hdr and tone mapping for sets that is under 1,000 nits until i read this topic. a nice read. quite informative.

To DavidH, i believe most 4k hdr sets won't be able to output 1,000 nits in 100% of the screen, maybe like 10% to 20% of the screen area. So, like you said maybe for tiny highlight, so we shouldn't worry too much about it.:)