Return to the CurtPalme.com main site CurtPalme.com Home Theater Forum
A forum with a sense of fun and community for Home Theater enthusiasts!
Products for Sale ] [ FAQ: Hooking it all up ] [ CRT Primer/FAQ ] [ Best/Worst CRT Projectors List ] [ Setup Tips & Manuals ] [ Advanced Procedures ] [ Newsletters ]

 
Forum FAQForum FAQ   SearchSearch   MemberlistMemberlist  Photo AlbumsPhoto Albums  RegisterRegister 
 MembershipClub Membership   ProfileProfile   Private MessagesPrivate Messages   Log inLog in 
Blu-ray disc release list and must-have titles. Buy the latest and best Blu-ray titles to show off in your home theater!

Hypothesis: Tone Mapped HDR with Lumagen and CRT Projectors?
Goto page 1, 2  Next
 
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> CRT Projectors
View previous topic :: View next topic  
Author Message
harry27




Joined: 04 Aug 2019
Posts: 22
Location: Los Angeles, CA, United States


PostLink    Posted: Tue Jan 12, 2021 12:21 am    Post subject: Hypothesis: Tone Mapped HDR with Lumagen and CRT Projectors? Reply with quote


        Register to remove this ad. It's free!
I've been reading and watching content about professional calibration with Lumagen Radiance processors. I stumbled upon the HDR Tone Mapping feature on newer Radiance processors. In short, my hypothesis is, could you use a Radiance to tone map HDR to SDR with CRT projectors? And is it even a good idea?

My primary source for this thought is an interview with Jason Dustal (Professional ISF Calibrator) and Jim Peterson (President of Lumagen), however I've seen some other videos explaining the tone mapping on Radiance processors. He explains that a projector displaying 100 nits can use a Radiance to basically grade/tone map the HDR image scene by scene or even frame by frame to SDR. Here is the link to the video and I wrote down the time to skip to. I highly recommend watching the part in the video talking about it, only 2 minutes long from the 11:50 mark.

https://www.youtube.com/watch?v=IV5KatkkN6w
(Skip to 11:50 in the video to see where he explains the Radiance tone mapping)

So my hypothesis. What if you use two Radiance processors, a new model for HDR tone mapping, and a second but older Radiance for 72hz output, and a processor that can be used to blend two CRT projectors together for additional brightness. The reason why two 9" CRT projectors are probably needed is that one projector probably isn't enough to get the luminance needed for consistently good HDR. Although theoretically a 9" CRT projector with 1000-1300 lumens can hit 80 to 95 nits on a 10% white window with 1.0 gain due to ABL (on a 120" screen), I have a hunch that the average picture level would still be too low for HDR tone mapped to SDR.

So what do you guys think? I personally don't think this is a practical setup. Newer projectors can display DCI P3 color gamut and a much higher luminance without any ABL limitations either. Also native 4K panels coupled with newer lens systems makes this setup seem even more archaic. However I like to come up with crazy and impractical setups even if they are over the top and not a practical at all.
Back to top
CIR Engineering




Joined: 25 Aug 2008
Posts: 4264
Location: Chicago USA & Berlin Germany


PostLink    Posted: Tue Jan 12, 2021 3:21 am    Post subject: Reply with quote

You don't need to "convert" HDR to SDR for CRT to work well with UHD sources. The Sony G90 can put out enough light to easily run a nice HDR image and I have done it many times and had it happily running in my own theater for over two years. I have never tried it with a Cine9 or 909, but I suspect they might also be capable. The key is being able to maintain focus while belching out tons of light and the G90 excels in this area due to its totally unique focus system. The Marquee's do not put out enough light because they can't maintain focus that bright unless you are one of the rare few who have a highly modified Marquee such as units I have seen at Mike Parker's home, so sorry 9500 guys.

The first benefit of CRT running UHD sources is HDR. The second bigger benefit is the fact that UHD BD is encoded in 10-bit YCbCr 420 instead of HD BD's inferior 8-bit YCbCr 420. This allows for much less noise in the video, but especially in the low light areas where much of that extra data is put to use. Detail in dark areas is exceptional on UHD BD's.

The downside of running UHD on a CRT is that UHD is encoded in Rec2020 (staying within the DCI-P3 D65 color gamut), but CRT can only produce a color gamut as large as Rec709. The extended color gamut of DCI-P3 IMHO is one of the best advantages of UHD, but with CRT this is unattainable. That said, many "high end" digital projectors including the Sony 995, 885, 695, and JVC NX5 do not have color filtration (just like colored elements on CRT) so they can't produce much more than Rec709 either. This is why I have an NX9 which is capable of full DCI-P3 along with the NX-7 and Sony 5000. The RS-4000 can do it too, but it is so loud while doing it that I have only had one client actually use it.

What this means is that colors that are encoded beyond Rec709 (and you do need the dark green and red celement to even make Rec709) will be clipped. This can result in less chroma resolution or sometimes even abrupt contouring.

You do NEED a Lumagen Radiance Pro processor to use their tone mapping as well. Only the Radiance Pro 42xx, 44xx, and upcoming future models can do HDR tone mapping. Here, a 2143 isn't going to cut it because it cannot accept UHD on the input, and it can only output 4K without HDR and without Rec2020. So with no UHD input you are dead in the water on a 21xx and there is no tone mapping feature in the menu because of that.

So HDR on CRT is totally doable with a Radiance Pro level processor even with a single G90. With a G90, to run HDR material you set the contrast at nearly 100% (or until it blooms) and set the green gain to MAX and balance the grayscale around it that way. It totally works well. You want to be absolutely sure to only use this memory in the G90 for HDR otherwise you will burn through tubes in no time. But, it's safe with HDR, because only the bright highlights will use the maximum output of the tubes, not the whole image. However, as you have noted, you can never have too much light for HDR be it digital or CRT projector, so a stack would only make it better.

craigr

_________________
*NEW JETI 1501-HiRes 2nm Spectroradiometer
JETI 1211 Spectroradiometer
Photo Research PR-650 Spectroradiometer
Klein K10-A Colorimeter
X-Rite i1Pro2 Spectroradiometer & Spyder Colorimeters *For JVC auto-calibration when Klein & Jeti are not applicable
Murideo Fresco SIX-G HDMI 2.x Multimedia Generator
Murideo Fresco SIX-A HDMI 2.x Analyzer
*NEW Light Illusion ColourSpace XPT Version β Color Calibration Software
Light Illusion LightSpace XPT Pro Version 10.x Color Calibration Software
*NEW OMARDRIS JVC Software Patch to use K10-A and Jeti with JVC OEM AutoCal Software!
Sencore CR7000 CRT Tube Analyzer / Rejuvenater
Authorized Dealer for Lumagen & just about everything worth buying Wink
www.CIR-Engineering.com - craigr@cir-engineering.com
Phone: 865-405-6892
Back to top
harry27




Joined: 04 Aug 2019
Posts: 22
Location: Los Angeles, CA, United States


PostLink    Posted: Tue Jan 12, 2021 5:04 am    Post subject: Reply with quote

Thanks for the response Craig, you really did explain everything in great detail. However I just want to clarify a couple things.

You said "You don't need to 'convert' HDR to SDR" but if it's not an SDR signal being sent to the projector then I'm confused what exactly is being sent to the G90 since it can't accept HDR metadata. I assumed that the Radiance Pro would be downscaling 4K 10-bit YCbCr 4:2:0 to 1080p 8-bit 4:4:4 and then outputs that to the G90 (or another CRT Projector). Then you'd use the Radiance's controls to dial in gamma and color to match HDR at 100 nits (or whatever peak luminance you can achieve depending on screen gain and size) as close as possible. I guess HDR tone mapped to 100 nits on a projector isn't technically SDR since projectors are usually calibrated at half that peak luminance for SDR.

The second thing is can the newer Radiance Pro processors output 72hz? I vaguely remember in another video that 72hz video output wasn't supported, however that might be for only 4K and not 1080p. That's the only reason why I thought using two Radiances were the way to go since you can create a tone mapped 1080p 24p image then convert that to 72hz using an older processor.

Other than those two small things, everything sounds great. I'm on the same page as you that I think the DCI P3 color gamut is the biggest upgrade for 4K content over traditional blu ray. I am just amazed that a single G90 can get the job done for HDR, I might have to try that in the future if I ever get the chance.


Last edited by harry27 on Wed Jan 13, 2021 12:49 am; edited 1 time in total
Back to top
ElTopo




Joined: 07 Nov 2006
Posts: 1607



PostLink    Posted: Tue Jan 12, 2021 11:47 am    Post subject: Reply with quote

I also use 4K UHD with an Oppo and a Marquee/Barco 9 incher.

Best thing about the Oppo 203 is that you can adjust nits over a wide range.

Works awesome.

_________________
Barco Cine 9 the one and only
Back to top
kal
Forum Administrator



Joined: 06 Mar 2006
Posts: 17850
Location: Ottawa, Canada

TV/Projector: JVC DLA-NZ7


PostLink    Posted: Tue Jan 12, 2021 1:23 pm    Post subject: Reply with quote

Hi Harry,

If you do end up being interested in a Radiance Pro unit - be aware that we have open box units available at discount prices and they still ship direct from Lumagen with the same warranty and support as "new" . Email me at kal@curtpalme.com for details. Extra info available too in the news on our main page: http://www.curtpalme.com/

Cheers!

Kal

_________________

Support our site by using our affiliate links. We thank you!
My basement/HT/bar/brewery build 2.0
Back to top
View user's photo album (18 photos)
CIR Engineering




Joined: 25 Aug 2008
Posts: 4264
Location: Chicago USA & Berlin Germany


PostLink    Posted: Tue Jan 12, 2021 4:46 pm    Post subject: Reply with quote

ElTopo wrote:
I also use 4K UHD with an Oppo and a Marquee/Barco 9 incher.

Best thing about the Oppo 203 is that you can adjust nits over a wide range.

Works awesome.

I totally forgot the Oppo's can do that! Not exactly as good as the dynamic adaptive tone mapping of the Lumagen's, but much less expensive.

craigr

_________________
*NEW JETI 1501-HiRes 2nm Spectroradiometer
JETI 1211 Spectroradiometer
Photo Research PR-650 Spectroradiometer
Klein K10-A Colorimeter
X-Rite i1Pro2 Spectroradiometer & Spyder Colorimeters *For JVC auto-calibration when Klein & Jeti are not applicable
Murideo Fresco SIX-G HDMI 2.x Multimedia Generator
Murideo Fresco SIX-A HDMI 2.x Analyzer
*NEW Light Illusion ColourSpace XPT Version β Color Calibration Software
Light Illusion LightSpace XPT Pro Version 10.x Color Calibration Software
*NEW OMARDRIS JVC Software Patch to use K10-A and Jeti with JVC OEM AutoCal Software!
Sencore CR7000 CRT Tube Analyzer / Rejuvenater
Authorized Dealer for Lumagen & just about everything worth buying Wink
www.CIR-Engineering.com - craigr@cir-engineering.com
Phone: 865-405-6892
Back to top
ElTopo




Joined: 07 Nov 2006
Posts: 1607



PostLink    Posted: Tue Jan 12, 2021 7:57 pm    Post subject: Reply with quote

Hey craigr,

did you try the Lumagen Pro with DTM on a CRT ?

_________________
Barco Cine 9 the one and only
Back to top
CIR Engineering




Joined: 25 Aug 2008
Posts: 4264
Location: Chicago USA & Berlin Germany


PostLink    Posted: Tue Jan 12, 2021 8:02 pm    Post subject: Reply with quote

ElTopo wrote:
Hey craigr,

did you try the Lumagen Pro with DTM on a CRT ?

Yes, it's running now on my G90. Setup two clients with it too.

craigr

_________________
*NEW JETI 1501-HiRes 2nm Spectroradiometer
JETI 1211 Spectroradiometer
Photo Research PR-650 Spectroradiometer
Klein K10-A Colorimeter
X-Rite i1Pro2 Spectroradiometer & Spyder Colorimeters *For JVC auto-calibration when Klein & Jeti are not applicable
Murideo Fresco SIX-G HDMI 2.x Multimedia Generator
Murideo Fresco SIX-A HDMI 2.x Analyzer
*NEW Light Illusion ColourSpace XPT Version β Color Calibration Software
Light Illusion LightSpace XPT Pro Version 10.x Color Calibration Software
*NEW OMARDRIS JVC Software Patch to use K10-A and Jeti with JVC OEM AutoCal Software!
Sencore CR7000 CRT Tube Analyzer / Rejuvenater
Authorized Dealer for Lumagen & just about everything worth buying Wink
www.CIR-Engineering.com - craigr@cir-engineering.com
Phone: 865-405-6892
Back to top
ElTopo




Joined: 07 Nov 2006
Posts: 1607



PostLink    Posted: Tue Jan 12, 2021 10:07 pm    Post subject: Reply with quote

Thanks.

Would you say it’s worth the money to add a Lumagen Pro for DTM ?

_________________
Barco Cine 9 the one and only
Back to top
CIR Engineering




Joined: 25 Aug 2008
Posts: 4264
Location: Chicago USA & Berlin Germany


PostLink    Posted: Wed Jan 13, 2021 1:56 am    Post subject: Reply with quote

ElTopo wrote:
Thanks.

Would you say it’s worth the money to add a Lumagen Pro for DTM ?

I don't know. It's a lot to spend. Myself and my clients who have done it all have CRT and digital UHD projectors. It's a tough call.

craigr

_________________
*NEW JETI 1501-HiRes 2nm Spectroradiometer
JETI 1211 Spectroradiometer
Photo Research PR-650 Spectroradiometer
Klein K10-A Colorimeter
X-Rite i1Pro2 Spectroradiometer & Spyder Colorimeters *For JVC auto-calibration when Klein & Jeti are not applicable
Murideo Fresco SIX-G HDMI 2.x Multimedia Generator
Murideo Fresco SIX-A HDMI 2.x Analyzer
*NEW Light Illusion ColourSpace XPT Version β Color Calibration Software
Light Illusion LightSpace XPT Pro Version 10.x Color Calibration Software
*NEW OMARDRIS JVC Software Patch to use K10-A and Jeti with JVC OEM AutoCal Software!
Sencore CR7000 CRT Tube Analyzer / Rejuvenater
Authorized Dealer for Lumagen & just about everything worth buying Wink
www.CIR-Engineering.com - craigr@cir-engineering.com
Phone: 865-405-6892
Back to top
CIR Engineering




Joined: 25 Aug 2008
Posts: 4264
Location: Chicago USA & Berlin Germany


PostLink    Posted: Wed Jan 13, 2021 2:15 am    Post subject: Reply with quote

It also depends on how much light you can get off your screen. Do you have something that can measure this? 75 nits would be adequate, but more is better for HDR.

craigr

_________________
*NEW JETI 1501-HiRes 2nm Spectroradiometer
JETI 1211 Spectroradiometer
Photo Research PR-650 Spectroradiometer
Klein K10-A Colorimeter
X-Rite i1Pro2 Spectroradiometer & Spyder Colorimeters *For JVC auto-calibration when Klein & Jeti are not applicable
Murideo Fresco SIX-G HDMI 2.x Multimedia Generator
Murideo Fresco SIX-A HDMI 2.x Analyzer
*NEW Light Illusion ColourSpace XPT Version β Color Calibration Software
Light Illusion LightSpace XPT Pro Version 10.x Color Calibration Software
*NEW OMARDRIS JVC Software Patch to use K10-A and Jeti with JVC OEM AutoCal Software!
Sencore CR7000 CRT Tube Analyzer / Rejuvenater
Authorized Dealer for Lumagen & just about everything worth buying Wink
www.CIR-Engineering.com - craigr@cir-engineering.com
Phone: 865-405-6892
Back to top
CIR Engineering




Joined: 25 Aug 2008
Posts: 4264
Location: Chicago USA & Berlin Germany


PostLink    Posted: Wed Jan 13, 2021 2:39 am    Post subject: Reply with quote

harry27 wrote:
Thanks for the response Craig, you really did explain everything in great detail. However I just want to clarify a couple things.

You said "You don't need to 'convert' HDR to SDR" but if it's not an SDR signal being sent to the projector then I'm confused what exactly is being sent to the G90 since it can't accept HDR metadata. I assumed that the Radiance Pro would be downscaling 4K 10-bit YCbCr 4:2:0 to 1080p 8-bit 4:4:4 and then outputs that to the G90 (or another CRT Projector). Then you'd use the Radiance's controls to dial in gamma and color to match HDR at 100 nits (or whatever peak luminance you can achieve depending on screen gain and size) as close as possible. I guess HDR tone mapped to 100 nits on a projector isn't technically SDR since projectors are usually calibrated at half that peak luminance for SDR.

The second thing is can the newer Radiance Pro processors output 72hz? I vaguely remember in another video that 72hz video output wasn't supported, however that might be for only 4K and not 1080p. That's the only reason why I thought using two Radiances were the way to go since you can create a tone mapped 1080p 24p image then convert that to 72hz using an older processor.

Other than those two small things, everything sounds great. I'm on the same page as you that I think the DCI P3 color gamut is the biggest upgrade for 4K content over traditional blu ray. I am just amazed that a single G90 can get the job done for HDR, I might have to try that in the future if I ever get the chance.

Great questions!

OK firstly any projector can "accept" HDR if you do it right. I setup the CRT HDR projector exactly the same way I setup the digital HDR projectors. This is what needs to be done to have the Lumagen do the tone mapping as well. Here we go...

Digital projectors and TV's go into an HDR mode that is preset from the factory when you send them HDR. This display manufacturer's HDR mode has its own tone mapping done by the display and restricts the settings that are available for calibration. It always looks like garbage.

So to circumvent this, what I do is to put the HDR signal into an SDR container and turn off the HDR flag using the Lumagen so that the display won't go into its HDR mode. This is also essential to use the Lumagen tone mapping instead of the display's native tone mapping. To elaborate, HDR is just a gamma curve, and dynamic adaptive tone mapping is just a gamma curve that adjusts in real time on a frame-by-frame basis after analyzing the image content (primarily brightness). So if you calibrate your projector's grayscale to D65 with a 2.4 gamma curve you are done with step one. After that what you do is set the Lumagen to output HDR with the HDR flag turned off. Now obviously this will not have an impact on a CRT because as you have noted there are no RGB transcoders for CRT that can even recognize the HDR flag anyway, but this is how it's done on both technologies. One a digital projector I select the output color gamut to be Rec2020, but on a CRT I tell the Lumagen to output Rec709. This tells the Lumagen to convert the Rec2020 coming into the Lumagen from the source to Rec709 on the output. If you don't do this everything will be hugely undersaturated.

Now to fully answer your question. The projector is using a 2.4 gamma. The Lumagen knows it's using a 2.4 gamma because this is the standard for UHD Rec2020 without HDR. All that has to be done at this point if for the Lumagen to simply manipulate the gamma to whatever brightness it needs to fully render the HDR while applying dynamic adaptive tone mapping signal inside the SDR 2.4 gamma curve. You don't give up a single thing! You get full HDR inside the SDR container! This is a special output mode that only Lumagen does and we call it SDH (HDR inside an SDR container).

The Moome boards, and I think the later HDMI to RGB transcoders, can accept 10 and 12-bit. So the output from the Lumagen should be set to 1080p 72Hz (or whatever) with YCbCr 422. This is natively 12-bit and offers the best image because there is little color up sampling between 420 and 422. The two look identical when done right and the Lumagen does it correctly.

About half the digital projectors I calibrate fall under 100 nits and many fall well under 100 nits. 100 nits doesn't directly have to do with anything. This is what tone mapping is for; to make HDR fit within the luminance range of any given display. Obviously if you have a brighter projector you can expand the dynamic range, but that's it. HDR is mastered between 1000-10000 nits, it's always about squeezing it into what the projector can go.

The adaptive dynamic tone mapping is in essence the gamma. We just don't have a static gamma curve anymore. In a way I hate it because it is not scientific like the old days when the numbers matched you were done. I have equations that I use to create multiples for the dynamic tone mapping to use based on the maximum luminance I get off the screen. But even that can vary greatly so to a large extent the dynamic tone mapping has to be done by eye. That said it's not too difficult provided you don't allow yourself to become seduced by an unnecessarily brighter image.

And yes, the Pro units can do 72Hz no problem and are also available with a 3D 3-pin mini-din plug should you also want to run 3D.

Now I bet there will be more questions Laughing

craigr

_________________
*NEW JETI 1501-HiRes 2nm Spectroradiometer
JETI 1211 Spectroradiometer
Photo Research PR-650 Spectroradiometer
Klein K10-A Colorimeter
X-Rite i1Pro2 Spectroradiometer & Spyder Colorimeters *For JVC auto-calibration when Klein & Jeti are not applicable
Murideo Fresco SIX-G HDMI 2.x Multimedia Generator
Murideo Fresco SIX-A HDMI 2.x Analyzer
*NEW Light Illusion ColourSpace XPT Version β Color Calibration Software
Light Illusion LightSpace XPT Pro Version 10.x Color Calibration Software
*NEW OMARDRIS JVC Software Patch to use K10-A and Jeti with JVC OEM AutoCal Software!
Sencore CR7000 CRT Tube Analyzer / Rejuvenater
Authorized Dealer for Lumagen & just about everything worth buying Wink
www.CIR-Engineering.com - craigr@cir-engineering.com
Phone: 865-405-6892
Back to top
gjaky




Joined: 05 Jun 2010
Posts: 2789
Location: Budapest, Hungary


PostLink    Posted: Wed Jan 13, 2021 6:44 am    Post subject: Reply with quote

Hi Craig,

If I understand correctly HDR on CRT is based on the "peak lumens" capability, that is eg. at 10% white window on a black background it can output say 3x the light than with a full field. But peak lumens are limited by the electronics in the projector where the average of the beam current is measured. So the same 10% window won't measure the same lightoutput if the rest of the frame is at an 50% gray (in SDR means).
So how do you take into account that how much "area" of the frame is allowed to be brighter than 100% (in SDR means)?

Also a side note, normally SDR video content is contained in the 16-235 range, in 8 bits realm, now all standard vide DACs are 8 bit capable at least, so the output range is 0-255, so in theory even without much voodoo the DAC output beyond 235 could be utilized, it would yield only extra 10% in the brightness upwards, but that is still something, no?

_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB, VIM-DB
Back to top
View user's photo album (1 photos)
Zebra




Joined: 02 Jul 2020
Posts: 86
Location: NJ USA


PostLink    Posted: Wed Jan 13, 2021 5:13 pm    Post subject: Reply with quote

I've yet to see any projector do a worthwhile job with HDR. That applies to almost all of the current gen of 4k home theater projectors.

Brightness is not the issue. At least, it's not the whole issue. It's the dynamic range. I.e. the ability to display super bright colors next to dark details without causing a washed out or overly dark image.

The marketing blurb for the most recent projector releases where they describe them as "real HDR" is in response to reviews of their previous efforts and acknowledging that having an HDR mode isn't the same as being HDR capable. Many of them produced an unbearably dark image where the content is demanding a dynamic range that is beyond their capability.

I've only seen decent HDR on OLED displays. The dynamic range on all current projector tech is nowhere near what Oled can do.

Given that people usually state that CRT projectors can't even match the ansi contrast of recent digital projectors, you've got no chance.

That doesn't mean there is no benefit of using a UHD blu ray. They have a bit rate of up to 100mbps vs just 40mbps for a regular Blu Ray or just 25mbps for "4k" Netflix.

If you are encoding the same movie footage twice with a 100gb limit for one file and a 40gb limit for the other, the 100gb file is going to be notably higher quality. It's the reason why the files used by theaters are more detailed than any home format. Regardless if it's output in 2k or 4k, they have bit rates up to 250mbps - so well over twice the information stored on a UHD blu Ray disc.

CRT projectors also have the benefit of producing less motion blur than LCOS, LCD and DLP. That higher motion resolution might really shine where you have that high quality content to show it off.

Getting a high dynamic range from CRT projectors is what those rastor calligraphic ones were all about. They apparently project a vector image over the regular raster image to make bright areas (like lights on a runway) look more realistic. This was necessary because regular CRT projectors don't have that kind of range.

If one had the means to feed a rastor calligraphic CRT projector with a suitable signal, they might be able to get closer to being HDR capable.
Back to top
harry27




Joined: 04 Aug 2019
Posts: 22
Location: Los Angeles, CA, United States


PostLink    Posted: Wed Jan 13, 2021 8:07 pm    Post subject: Reply with quote

CIR Engineering wrote:


Now I bet there will be more questions Laughing

craigr


Surprisingly not too many questions besides the smallest of things (like 2.4 gamma vs the BT. 1886 curve). Putting the HDR signal into an SDR container with 2.4 gamma with the Lumagen's dynamic tone mapping is roughly the idea I had in my head. I really appreciate the detail you went into for the 12-bit 422 output, that makes a lot of sense when you explained it. With the 12-bit output I bet gradients probably look very smooth.

The 100 nit mark isn't necessary like you said (75 nits is adequate), it was just the number Jim kept saying and it's a nice whole even number that sounds nice. I'm amazed that even the digital projectors you calibrate usually fall under 100 nits for HDR, but now thinking about it with some hindsight, even the Dolby Vision Cinema projectors only output 106 nits, so for home use 70-100 nits sounds great with dynamic tone mapping.

I also miss the old days with gamma, much simpler back then for calibration, but also having the ability to customize gamma for different room environments was so helpful. Now it's almost impossible to adjust that on TVs in HDR mode and you have to rely on the TV's dynamic tone mapping, and I trust a Lumagen much more with tone mapping than any TV or projector on the market today. Tone mapping is a complicated balancing act, but from what I heard the Lumagen does a fantastic job of keeping the creator's intent.

Happy to know that the Pro units can output 72hz Smile that simplifies this setup a lot.

Really thanks for the explanation and the detail you went into, if I ever get a Radiance Pro I'm definitely going to try HDR on my G90.
Back to top
pureaudio




Joined: 29 Mar 2015
Posts: 37



PostLink    Posted: Sat Jan 30, 2021 6:20 pm    Post subject: Reply with quote

All the movies can be found on 1080P Blu Ray, so no need to convert the UHD HDR edition to a CRT, just put the right disc in the player and your good to go, and just saved yourself a lot of money on expensive processors.
Back to top
CIR Engineering




Joined: 25 Aug 2008
Posts: 4264
Location: Chicago USA & Berlin Germany


PostLink    Posted: Sat Jan 30, 2021 7:25 pm    Post subject: Reply with quote

harry27 wrote:
CIR Engineering wrote:


Now I bet there will be more questions Laughing

craigr


Surprisingly not too many questions besides the smallest of things (like 2.4 gamma vs the BT. 1886 curve). Putting the HDR signal into an SDR container with 2.4 gamma with the Lumagen's dynamic tone mapping is roughly the idea I had in my head. I really appreciate the detail you went into for the 12-bit 422 output, that makes a lot of sense when you explained it. With the 12-bit output I bet gradients probably look very smooth.

The 100 nit mark isn't necessary like you said (75 nits is adequate), it was just the number Jim kept saying and it's a nice whole even number that sounds nice. I'm amazed that even the digital projectors you calibrate usually fall under 100 nits for HDR, but now thinking about it with some hindsight, even the Dolby Vision Cinema projectors only output 106 nits, so for home use 70-100 nits sounds great with dynamic tone mapping.

I also miss the old days with gamma, much simpler back then for calibration, but also having the ability to customize gamma for different room environments was so helpful. Now it's almost impossible to adjust that on TVs in HDR mode and you have to rely on the TV's dynamic tone mapping, and I trust a Lumagen much more with tone mapping than any TV or projector on the market today. Tone mapping is a complicated balancing act, but from what I heard the Lumagen does a fantastic job of keeping the creator's intent.

Happy to know that the Pro units can output 72hz Smile that simplifies this setup a lot.

Really thanks for the explanation and the detail you went into, if I ever get a Radiance Pro I'm definitely going to try HDR on my G90.

BT. 1886 should not be used for the HDR tone mapping container because all of the tone mapping algorithms are based on a 2.4 gamma which is the industry standard. With the Lumagen's adaptive dynamic tone mapping it will also tone map the low end and can easily bring out details that are apparent in 10-bit transfers on UHD BD's. Specifically, you would adjust the "HDR Parameters" "Low" "Ratio" setting. The higher the ratio here the lower the effective display max light parameter becomes. The lower the effective display max light parameter the brighter the image will get (just like lowering gamma). So in darker scenes shadow details will come out as they should, or could be made to come out more than they should if one desires.

craigr

_________________
*NEW JETI 1501-HiRes 2nm Spectroradiometer
JETI 1211 Spectroradiometer
Photo Research PR-650 Spectroradiometer
Klein K10-A Colorimeter
X-Rite i1Pro2 Spectroradiometer & Spyder Colorimeters *For JVC auto-calibration when Klein & Jeti are not applicable
Murideo Fresco SIX-G HDMI 2.x Multimedia Generator
Murideo Fresco SIX-A HDMI 2.x Analyzer
*NEW Light Illusion ColourSpace XPT Version β Color Calibration Software
Light Illusion LightSpace XPT Pro Version 10.x Color Calibration Software
*NEW OMARDRIS JVC Software Patch to use K10-A and Jeti with JVC OEM AutoCal Software!
Sencore CR7000 CRT Tube Analyzer / Rejuvenater
Authorized Dealer for Lumagen & just about everything worth buying Wink
www.CIR-Engineering.com - craigr@cir-engineering.com
Phone: 865-405-6892
Back to top
CIR Engineering




Joined: 25 Aug 2008
Posts: 4264
Location: Chicago USA & Berlin Germany


PostLink    Posted: Sat Jan 30, 2021 7:31 pm    Post subject: Reply with quote

harry27 wrote:
CIR Engineering wrote:


Now I bet there will be more questions Laughing

craigr


Surprisingly not too many questions besides the smallest of things (like 2.4 gamma vs the BT. 1886 curve). Putting the HDR signal into an SDR container with 2.4 gamma with the Lumagen's dynamic tone mapping is roughly the idea I had in my head. I really appreciate the detail you went into for the 12-bit 422 output, that makes a lot of sense when you explained it. With the 12-bit output I bet gradients probably look very smooth.

The 100 nit mark isn't necessary like you said (75 nits is adequate), it was just the number Jim kept saying and it's a nice whole even number that sounds nice. I'm amazed that even the digital projectors you calibrate usually fall under 100 nits for HDR, but now thinking about it with some hindsight, even the Dolby Vision Cinema projectors only output 106 nits, so for home use 70-100 nits sounds great with dynamic tone mapping.

I also miss the old days with gamma, much simpler back then for calibration, but also having the ability to customize gamma for different room environments was so helpful. Now it's almost impossible to adjust that on TVs in HDR mode and you have to rely on the TV's dynamic tone mapping, and I trust a Lumagen much more with tone mapping than any TV or projector on the market today. Tone mapping is a complicated balancing act, but from what I heard the Lumagen does a fantastic job of keeping the creator's intent.

Happy to know that the Pro units can output 72hz Smile that simplifies this setup a lot.

Really thanks for the explanation and the detail you went into, if I ever get a Radiance Pro I'm definitely going to try HDR on my G90.

The most light I have ever had to work with on a projector was 2000 nits off a Barco Thor on a very large scope screen with negative gain, it was glorious except for the lack of black level. My own system with a 128" wide scope screen, Paladin DCR, and NX9 runs around 125 nits. I did an NX9 Monday and Tuesday running a Paladin DCR on a 128" wide Viewteck high power 2.7 gain screen and got 200 nits. I've done quite a few RS4000's, Sony 995 and 885's... where the maximum luminance was under 100 nits. The lowest I have worked with in HDR is 65 nits, but 75-95 is not at all unusual. I would say 100 nits is about average though.

craigr

_________________
*NEW JETI 1501-HiRes 2nm Spectroradiometer
JETI 1211 Spectroradiometer
Photo Research PR-650 Spectroradiometer
Klein K10-A Colorimeter
X-Rite i1Pro2 Spectroradiometer & Spyder Colorimeters *For JVC auto-calibration when Klein & Jeti are not applicable
Murideo Fresco SIX-G HDMI 2.x Multimedia Generator
Murideo Fresco SIX-A HDMI 2.x Analyzer
*NEW Light Illusion ColourSpace XPT Version β Color Calibration Software
Light Illusion LightSpace XPT Pro Version 10.x Color Calibration Software
*NEW OMARDRIS JVC Software Patch to use K10-A and Jeti with JVC OEM AutoCal Software!
Sencore CR7000 CRT Tube Analyzer / Rejuvenater
Authorized Dealer for Lumagen & just about everything worth buying Wink
www.CIR-Engineering.com - craigr@cir-engineering.com
Phone: 865-405-6892
Back to top
CIR Engineering




Joined: 25 Aug 2008
Posts: 4264
Location: Chicago USA & Berlin Germany


PostLink    Posted: Sat Jan 30, 2021 7:42 pm    Post subject: Reply with quote

gjaky wrote:
Hi Craig,

If I understand correctly HDR on CRT is based on the "peak lumens" capability, that is eg. at 10% white window on a black background it can output say 3x the light than with a full field. But peak lumens are limited by the electronics in the projector where the average of the beam current is measured. So the same 10% window won't measure the same lightoutput if the rest of the frame is at an 50% gray (in SDR means).
So how do you take into account that how much "area" of the frame is allowed to be brighter than 100% (in SDR means)?

Also a side note, normally SDR video content is contained in the 16-235 range, in 8 bits realm, now all standard vide DACs are 8 bit capable at least, so the output range is 0-255, so in theory even without much voodoo the DAC output beyond 235 could be utilized, it would yield only extra 10% in the brightness upwards, but that is still something, no?

The answer to your first question is to handle the difference in CRT luminance outputs with respect to content by meticulous observation and adjusting by eye. I typically start by setting the high display max light to ~5x-6x the actual measured display max light and the effective low display max light ratio to about 1.5x the actual measured display max light. Then I look at a number of scenes off UHD discs that I am intimately familiar with and adjust from there. If the entirety of the image looks too dark than I reduce the display max light setting to brighten things up and recalculate and apply the effective low display max light to stay close to 1.5x of actual (or the opposite if the image seems too bright. Once I have the high master display max light where I want it, I then increase or decrease the low display max light by eye to make darker scenes look correct. Usually I find this will fall between 1x-2x the actual display max light, but sometimes I may go as high as 3x if I think the image looks washed out in dark scenes.

Moome's DAC's will accept YCbCr 422 which is 12-bit. Digital component for video does not have a legal range for "PC levels," so 0-255 is not allowed. That said, this will make no difference on the display's maximum light output. The limiting factor here is where does the CRT projector start to bloom. You can hit blooming with 16-235 or 0-255 so there is no increased light by using PC levels. Also, PC white is the same brightness as video white so again no difference.

Does this make sense?

craigr

_________________
*NEW JETI 1501-HiRes 2nm Spectroradiometer
JETI 1211 Spectroradiometer
Photo Research PR-650 Spectroradiometer
Klein K10-A Colorimeter
X-Rite i1Pro2 Spectroradiometer & Spyder Colorimeters *For JVC auto-calibration when Klein & Jeti are not applicable
Murideo Fresco SIX-G HDMI 2.x Multimedia Generator
Murideo Fresco SIX-A HDMI 2.x Analyzer
*NEW Light Illusion ColourSpace XPT Version β Color Calibration Software
Light Illusion LightSpace XPT Pro Version 10.x Color Calibration Software
*NEW OMARDRIS JVC Software Patch to use K10-A and Jeti with JVC OEM AutoCal Software!
Sencore CR7000 CRT Tube Analyzer / Rejuvenater
Authorized Dealer for Lumagen & just about everything worth buying Wink
www.CIR-Engineering.com - craigr@cir-engineering.com
Phone: 865-405-6892
Back to top
CIR Engineering




Joined: 25 Aug 2008
Posts: 4264
Location: Chicago USA & Berlin Germany


PostLink    Posted: Sat Jan 30, 2021 8:03 pm    Post subject: Reply with quote

Zebra wrote:
I've yet to see any projector do a worthwhile job with HDR. That applies to almost all of the current gen of 4k home theater projectors.

Brightness is not the issue. At least, it's not the whole issue. It's the dynamic range. I.e. the ability to display super bright colors next to dark details without causing a washed out or overly dark image.

The marketing blurb for the most recent projector releases where they describe them as "real HDR" is in response to reviews of their previous efforts and acknowledging that having an HDR mode isn't the same as being HDR capable. Many of them produced an unbearably dark image where the content is demanding a dynamic range that is beyond their capability.

I've only seen decent HDR on OLED displays. The dynamic range on all current projector tech is nowhere near what Oled can do.

Given that people usually state that CRT projectors can't even match the ansi contrast of recent digital projectors, you've got no chance.

It is not possible for me to disagree more.

The quality of the dynamics of HDR is entirely due to its tone mapping. Yes, most projector's native tone mapping, especially Sony, is abysmal. However, the point of proper tone mapping is to make the sources native dynamic range fit within the range of a given display. JVC now supports its own native dynamic tone mapping that does an impressive job on its own. Lumagen does truly exception adaptive dynamic tone mapping that really squeezes everything out of any given display. You say with CRT you don't have a chance, but I have had excellent results so you are wrong.

Furthermore, the tone mapping on OLED is often exaggerated and overly bright which seduces a viewer into thinking the image is better; the oldest trick in the book. Anyone will say an image that's brighter is better looking when blindly asking, but is it actually better or correct? One prime example is in Lucy, when Morgan Freeman is lecturing. The camera moves to the back of the room so that you can see the attendees paper notebooks on which they are writing. On an OLED these white papers do not look like paper at all, but actually look like they are emitting light (like they are light sources), not reflecting ambient light in their room. This does not look natural at all, but the casual observer will think it's great just because the image is excessively bright.

craigr

_________________
*NEW JETI 1501-HiRes 2nm Spectroradiometer
JETI 1211 Spectroradiometer
Photo Research PR-650 Spectroradiometer
Klein K10-A Colorimeter
X-Rite i1Pro2 Spectroradiometer & Spyder Colorimeters *For JVC auto-calibration when Klein & Jeti are not applicable
Murideo Fresco SIX-G HDMI 2.x Multimedia Generator
Murideo Fresco SIX-A HDMI 2.x Analyzer
*NEW Light Illusion ColourSpace XPT Version β Color Calibration Software
Light Illusion LightSpace XPT Pro Version 10.x Color Calibration Software
*NEW OMARDRIS JVC Software Patch to use K10-A and Jeti with JVC OEM AutoCal Software!
Sencore CR7000 CRT Tube Analyzer / Rejuvenater
Authorized Dealer for Lumagen & just about everything worth buying Wink
www.CIR-Engineering.com - craigr@cir-engineering.com
Phone: 865-405-6892


Last edited by CIR Engineering on Sun Jan 31, 2021 10:48 pm; edited 3 times in total
Back to top
Display posts from previous:   
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> CRT Projectors All times are GMT
Goto page 1, 2  Next
Page 1 of 2
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum