AVS Discussions

HDR and projection

HDR and projection
« on: January 07, 2017, 12:17:16 PM »
Hey Everyone. Just thought I'd chime in with some thoughts and experiments I've been running the last few days. As all are more than aware of here HDR on projection is sort of a work in progress right now. I haven't had the chance to play with HDR with the newer Sony offerings since they've revamped with firmware, so most of these comments are based on my time with the JVC X750. Initially most were using JVC's recommended settings and then going from there using a fleeting amount of test patterns that are available to dial in a picture that looks good. The problem there is while it may look good, it is still a best guess approach at this point derived mainly from trial and error with other's settings or successes. The next step was converting the HDR output to a SDR output but retaining the WCG capacity of the video signal. This seems to work best with the Panasonic player at the moment, but even after many weeks of trial and error I still see issues with gamma, mild clipping and more with this solution. Since the WCG portion of the movie is mastered in relation to the HDR EOTF, I imagine we are still seeing an improper conversion down to SDR levels as you would have to take into account the change in color volume from the intended display luminance. Sure it can look good still, but I would almost argue that the same look could be obtained with standard Blu-ray by just using a wider color preset on the projector. Call me a video snob but I prefer accurate to intent images rather than images that just look good.

So I decided to try something that no one ever seems to consider or try, telling the player NO for HDR and having it map down to standard gamma and REC709 color. This still preserves the resolution bump offered by UHD and the 10-bit video. But the UHD standard was also delivered with actual specifications on how to do this conversion, unlike converting to SDR with 2020. Using this method I get a proper conversion for both gamma and color to SDR, and can view the movie with a proper calibration. I have to say, so far I'm far more impressed with this as the image never has that "it looks great, but there are a few things that still look off". Like everyone else I am hoping that solutions will come that deliver an ACCURATE fold down to SDR with 2020 color, but it appears we are not there yet. I am also anxious to see what can be achieved with a Radiance Pro that tone maps HDR down to the projector's true output in what appears to be a much more intelligent fashion. Until then, I think I'm going to stick with this (other than continuing experimentation with the other options for testing purposes) for now and just sit back and enjoy.
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Sound and Vision

Re: HDR and projection
« Reply #1 on: January 07, 2017, 01:52:31 PM »
Hi Kris,

Are you doing this on the Oppo 203?  With the 203, I tried turning off HDR and using Rec 709 on a UHD BD, but it still looked a bit too dark compared to the BD counterpart. 
« Last Edit: January 07, 2017, 01:55:05 PM by DavidHir »

Re: HDR and projection
« Reply #2 on: January 07, 2017, 02:11:38 PM »
Kris,

For projectors sake, how many nits will we need to benefit from HDR? Do we actually need 1000nits? Some setups can get up to 300 nits but apparently, that's not enough.

Re: HDR and projection
« Reply #3 on: January 07, 2017, 02:20:53 PM »
I was going to ask the same. I wonder if Brightness +8 on the 203 with HDR OFF would brighten the image properly and be more accurate than HDR Strip.

Re: HDR and projection
« Reply #4 on: January 07, 2017, 03:08:25 PM »
I'm using HDR off with the latest public beta FW for the Oppo 203 with no issues in darkness. Have looked at several Blu-rays. Using the exact same calibration I use for standard Blu-ray (709 with BT1886 gamma). Colors look slightly more saturated than the Blu-ray versions do, but only slightly. Noticed this mostly with Revenant and Sicario so far (Sicario doesn't have the washed out appearance that the Blu-ray does in the opening sequence).
Technical Editor/Writer
Sound and Vision

Re: HDR and projection
« Reply #5 on: January 07, 2017, 03:30:45 PM »
Thanks, very helpful. Its nice to have people that can't use HDR or dont want to currently, to be able to have alternatives.

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Re: HDR and projection
« Reply #6 on: January 07, 2017, 03:55:26 PM »
Hey Everyone. Just thought I'd chime in with some thoughts and experiments I've been running the last few days. As all are more than aware of here HDR on projection is sort of a work in progress right now. I haven't had the chance to play with HDR with the newer Sony offerings since they've revamped with firmware, so most of these comments are based on my time with the JVC X750. Initially most were using JVC's recommended settings and then going from there using a fleeting amount of test patterns that are available to dial in a picture that looks good. The problem there is while it may look good, it is still a best guess approach at this point derived mainly from trial and error with other's settings or successes. The next step was converting the HDR output to a SDR output but retaining the WCG capacity of the video signal. This seems to work best with the Panasonic player at the moment, but even after many weeks of trial and error I still see issues with gamma, mild clipping and more with this solution. Since the WCG portion of the movie is mastered in relation to the HDR EOTF, I imagine we are still seeing an improper conversion down to SDR levels as you would have to take into account the change in color volume from the intended display luminance. Sure it can look good still, but I would almost argue that the same look could be obtained with standard Blu-ray by just using a wider color preset on the projector. Call me a video snob but I prefer accurate to intent images rather than images that just look good.

So I decided to try something that no one ever seems to consider or try, telling the player NO for HDR and having it map down to standard gamma and REC709 color. This still preserves the resolution bump offered by UHD and the 10-bit video. But the UHD standard was also delivered with actual specifications on how to do this conversion, unlike converting to SDR with 2020. Using this method I get a proper conversion for both gamma and color to SDR, and can view the movie with a proper calibration. I have to say, so far I'm far more impressed with this as the image never has that "it looks great, but there are a few things that still look off". Like everyone else I am hoping that solutions will come that deliver an ACCURATE fold down to SDR with 2020 color, but it appears we are not there yet. I am also anxious to see what can be achieved with a Radiance Pro that tone maps HDR down to the projector's true output in what appears to be a much more intelligent fashion. Until then, I think I'm going to stick with this (other than continuing experimentation with the other options for testing purposes) for now and just sit back and enjoy.

I'm getting good results using HDR - SDR BT.2020, but when I get some time I just might try this and see. 
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Re: HDR and projection
« Reply #7 on: January 07, 2017, 04:58:17 PM »
Ive been happy too with SDR 2020, but have not done side by side. I guess Kris has and I get his point, where we have had the ignorance is bliss man this looks good take, once you compare to what it should be it brings up some good points.


The first movie I watched SDR 2020 was TMNT 2, after several unhappy attempts at watching movies with HDR. I was blown away at the detail, and the blacks, I never looked back.

Re: HDR and projection
« Reply #8 on: January 07, 2017, 07:14:33 PM »
I assume that once DV is included in BR, and we get players that can send that information to the projector that we will be facing the same issues, in a DV capable projector, say maybe 2017 sony's??

Re: HDR and projection
« Reply #9 on: January 07, 2017, 07:38:59 PM »
...
So I decided to try something that no one ever seems to consider or try, telling the player NO for HDR and having it map down to standard gamma and REC709 color. This still preserves the resolution bump offered by UHD and the 10-bit video.
...

I wasn't aware you would still get 10 bit video.  Good to know.

Thanks.


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Re: HDR and projection
« Reply #10 on: January 07, 2017, 10:00:00 PM »
I assume that once DV is included in BR, and we get players that can send that information to the projector that we will be facing the same issues, in a DV capable projector, say maybe 2017 sony's??

Doubtful we will have projectors that can do DV HDR anytime soon. 2020 maybe ?
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Re: HDR and projection
« Reply #11 on: January 07, 2017, 10:04:37 PM »
Ive been happy too with SDR 2020, but have not done side by side. I guess Kris has and I get his point, where we have had the ignorance is bliss man this looks good take, once you compare to what it should be it brings up some good points.


The first movie I watched SDR 2020 was TMNT 2, after several unhappy attempts at watching movies with HDR. I was blown away at the detail, and the blacks, I never looked back.

I have done side by side ( more like one, then the other, then back again ) between first 4K BR with HRD vs regular Blu Rays, and then 4K HDR - SDR BT.2020 vs Blu Ray. That's how I know my picture is close, since I have my projector dialed in for regular 1080p content. I may do some more comparisons, which is easy with a Blu Ray player and a 4K Blu Ray player in my rack.   
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We carry projectors, screens, speakers, receivers etc. !!
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Re: HDR and projection
« Reply #12 on: January 08, 2017, 09:03:11 AM »
I have done side by side ( more like one, then the other, then back again ) between first 4K BR with HRD vs regular Blu Rays, and then 4K HDR - SDR BT.2020 vs Blu Ray. That's how I know my picture is close, since I have my projector dialed in for regular 1080p content. I may do some more comparisons, which is easy with a Blu Ray player and a 4K Blu Ray player in my rack.   

Are you using the Oppo or Panny 900?

Re: HDR and projection
« Reply #13 on: January 08, 2017, 09:26:30 AM »
Nobody has a SMPTE 2084 gamma curve measured on a projector?.. Or are you all just eyebaling it.?

I have 0-100% IRE patterns with 10% jumps for grayscale and gamma calibration on a SD card that the player read as a UHD BT2020 HDR source, and i can output it 1080P REC 709 SDR, and see how it responds to the SMPTE 2084 gamma curve that the movies are mastered to.
If someone want the files ill be happy to send a link, so you can post some measurements and move the hole debate to a more objective place.
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Re: HDR and projection
« Reply #14 on: January 08, 2017, 10:14:47 AM »
Are you using the Oppo or Panny 900?

Panny UB900.
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