Panel: New 4K Ultra HDTVs Are Good First Step For HDR
Looking to arrive at a standard of performance for new generation 4K Ultra HDTVs with high dynamic range (HDR) and a wide color gamut, Samsung recently commissioned the development of a new Ultra HD HDR Reference Test Disc and corresponding PC-based work flow to help product reviewers, professional calibrators and others properly test and evaluate new products coming to market.
Prior to presenting the disc to invited attendees, Samsung provided a Q-&-A panel session with a number of TV experts from Samsung, along with Florian Freidrich, television technology expert, who developed the workflow and test patterns used to calibrate the HDR-10 protocol accurately.
Among many other things, the disc uses motion in test patterns to get around the problem of where most HDR-capable TVs automatically begin to ramp down peak brightness levels a few seconds after achieving them in order to safe guard against damaging the panel lighting system in LED LCD TVs or the self-emissive screen in OLED displays.
The discussion was led by Chris Chinnock, principal of InSight Media, a display technology research firm, and included [pictured at top from left]: Steve Panosian, responsible for product marketing management at Samsung Electronics America; Gerard Catapano, Samsung QA Lab director; Jason Hartlove, CEO of Nanosys, Samsung’s partner in quantum dot development; and Freidrich.
Read the Q-&-A panel discussion after the jump:
Who do you view as the target customer for the HDR Reference disc?
Florian Freidrich: Anyone who is interested in knowing what their TV is doing.
It is a challenge to set up these devices correctly and make sure everything’s working correctly in order to ensure we deliver the maximum performance that is possible. In order to understand the limitations on the system, you need tools to evaluate it, and that’s one of the big goals of the disc. To evaluate and as soon as you see issues with the TV to understand what is right for these devices …so in some cases tone mapping makes sense and in other cases perhaps there are devices that should not handle the HDR at all. That’s just understanding that the metadata is not sufficient enough for representing HDR. So, actually we want devices that are capable of reproducing what the system’s capable of doing. In order to see if that is possible a list [televisions by performance capabilities] should help. That is true for everyone who is interested in HDR. It’s manufacturers, anyone involved in post-production, enthusiasts, and any others are in need of this.
Q: What was the need that you identified at the time that you started developing your reference disc a year ago?
Freidrich: I saw that this was a quite interesting system. So it’s a container of innovations, however, there are some missing parts. It starts with how to inject the metadata into the HEVC path. How do I inject metadata into HDMI? These required two pieces of software to inject the metadata into HEVC and into HDMI. That’s where it started, and I realized that having a disc which takes out all of the system variables is something that could be quite helpful.
Q: You talk about some of the patterns that you have included. What are some of the strongest patterns that you’ve got on there?
Freidrich: We have to understand that none of the [standard dynamic rage] SDR patterns work anymore in the HDR world. It’s exactly the same need that we had for SDR Rec. 709. It starts with adjusting black levels and adjusting contrast, and seeing where our system limitations are and where they belong, and that we are not losing headroom; we are not losing contrast or color saturation or finding over saturation. So, one thing that I found very interesting was the clipping pattern or tone mapping. So, you can see where the system’s clipping or where the system’s tone mapping, where the clipping’s starting, all these kinds of things, are very helpful. Another thing is the color bars which allow us to see any color saturation and it lets you see if your system is in the right domain. For example, I have seen an Ultra HD Blu-ray player [not the Samsung UBD-K8500] that would convert to RGB but would use the wrong math to do it. So, in this case you were able to see a good representation of Full HD Blu-ray discs, but inappropriate colors for HDR. These offer some interesting patterns.
The reference disc is a tool that can be used with any brand of TV, but any brand of Blu-ray player? Probably not, because I’ve seen playback problems.
Q: What do you think about the whole issue of getting a consistent image given the great variety of mastering content environments and this great variety of televisions and capabilities?
Steve Panosian: Today, we are trying to define for consumers what 4K is, and where the color experience benefit is. For the consumer it is all about this new buzz for HDR and the more `wow’ looking picture it provides. But as far as the Reference Disc goes, we are relying on this group here [pointing to the audience] and others to help the customer understand what they are looking at and bought into, and why it’s important to understand the variables.
Q: So, is it a little too complex at this juncture to get into the differences in the various flavors of HDR.
Panosian: My philosophy is that we should promote a class of product that describes HDR and all this other stuff at this point in time. If something can’t pass the mom, dad, sister, brother, friends and neighbor test, then we have a problem. And that’s why we need to slow down. Before we even get to the next step, if consumers don’t understand what they’re buying into today, then I don’t even want to talk about what’s next.
Gerard Catapano: For video, I don’t think most people understand yet what good quality is. We’ve come a long way from seeing snow and rolling vertical lines. Once we got over that, then perception shifted to consistency of color. So it’s coming along and the level of acceptance is much higher today than it’s ever been.
Panosian: You really can’t look at HDR and SDR side by side and say which one’s right and wrong because what’s happening when these colorists are stepping into their suites to read something is the playground’s become a lot bigger. There’s more color, more dynamic range, and other variables, all of which could lead the creative experience in a completely different direction. It has nothing to do with what is right and wrong. How do you guess on a TV that you are testing, what was the director’s artistic intent?
Freidrich: The answer to this is very complex. There are many layers and variables. Even when it comes down to the mastering monitor. Even the most expensive mastering monitor that you can purchase today is not perfect. If you compare the measurements to what TVs do, you might find that some of the TVs are similar, and many of the mastering houses are using consumer displays in addition to their normal environment in order to see what the consumer experience at home would be. The big goal, of course, is to enhance the experience. And you need to look at all of the little factors that could influence the experience. The system is not completed. It is getting better and better, but we are at a very interesting point in time where displays are outperforming what we see in SDR, if there is better content and there is better mastering.
A couple of years from now when additional standards are implemented, for example, SMPTE 2094, which is taking care of some of the different aspects of tone mapping for different TVs and different scenes and all of that, it will get better and better. We are just at the beginning of the experience.
Q: Let’s talk about what quantum dots can do.
Jason Hartlove: Quantum dots are a unique nanocrystal with a unique structure in nature, which we knit very close to pure colors of light with very high efficiency, and which are very low cost to manufacture. So, what this has enabled is for us to work very close together with companies like Samsung, who incorporate this technology to allow for purer primaries in the set. It works with the RGB system and what is conventionally available with LED back lighting technology.
As a result of that, we have a much brighter image in any given primary than we’ve had before. For example, a lot of focus lately has been on use of a white sub pixel as a way to get higher brightness out of the system. The white sub pixel approach throws into a pixel a white sub pixel along with the standard red, green and blue sub pixels. When you have this altered image you are getting brighter signal out of the white sub pixel than you are out of the red, green and blue sub pixels. But you can’t get a brighter color out of the white sub pixel. You can only get white. So, what you get is a system that might say it’s capable of 1,000 Nits, but it’s only capable of 1,000 Nits at that light point that the white sub pixel is at. So, when you watch a picture in a nice bright room, you are seeing a not very interesting image of a fire or the sun or anything else, which are generally seen in very bright colored lights.
So quantum dots allow manufacturers like Samsung to be able to make these very, very bright high dynamic range output levels with dynamic colors as part of the consumer experience.
One other thing I wanted to mention is that we are starting to work now, and have one reference monitor out in the market and there will be more reference monitors coming in the next few years using quantum dots as well. So, this should enable content providers, and color graders to use the same kind of color technologies in their grading for content that will be seen on HDR sets.
Q: You have mentioned that you are working on technology that puts quantum dots directly into color filters so that you would basically have a broader back light with quantum dot support colors. Can you tell us more about that?
Hartlove: Sure. Quantum dots use very high efficiency converged photons from one wave length, as long as it’s a short wave length, to a longer wavelength. So, for example, when we stimulate a quantum dot that has been manufactured to produce a green light, when we stimulate that with a blue light source it is always going to produce the exact same green light. So, what we are doing today is creating a perfect red, green and blue back light behind the LCD. This gives us perfect peaks of red, green and blue, ideally located. Then the photons go forward through the LCD shutter to the color filter – the sub pixel – the sub pixel color filter basically throws away two thirds of the photons that come forward, in rough numbers. At any sub pixel location, you are either allowing red or green or blue to come through. So, if instead of filtering that light energy, the conversion to the proper color comes in front of the sub pixel then we have photons come forward that convert and project the light output needs. We have the potential of seeing a 3x improvement in system efficiency. This means, dramatic increases in potential peak brightness or dramatic reductions in power consumption or dramatic improvements in cost. We have a very strong program working on the technology and we hope to see it in the near future.
By Greg Tarr
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