Welcome to www.avsforum.com
Can we continue to use your data to tailor ads for you?

Our partners will collect data and use cookies for ad personalization and measurement.

Learn more about how we use cookies

AVS Forum | Home Theater Discussions And Reviews
Sign-up now! It's free and easy. Registration ►

Spears & Munsil UHD HDR Benchmark Disc - Discussion

08:07 PM 09-25-2019
#511
Rolls-Royce
Quote:
Originally Posted by mombasa123
Aye, am beginning to think a pattern generator is the only way to go which, for me, means an expensive one unless the RPi4 can do YCbCr as my Samsungs RGB->YCbCr color space conversion is pants.
If you search online, you may be able to find something like a used Sencore, AVLab TPG by DVDO, or Accupel for a better price. They won't be cheap, but far less expensive than new. The issue then would be if CalMAN Home supports their use.

Addendum: I just checked. Surprise, surprise! CalMAN Home supports the Accupel line and the AVLab TPG.
10:35 AM 09-26-2019
#512
sspears
Quote:
Originally Posted by Dominic Chan
Here’s one recent post by Kris Deering on the topic of HDR on projectors:
https://www.avsforum.com/forum/24-di...l#post58505896
Quote:
Originally Posted by Kris Deering
(snip)...but that metadata (if correct) is telling you its worse case scenario for the brightest scene in the content. But that scene could literally be a few seconds of the entire movie and you've now compromised the rest of the movie for literally what could be a few seconds at best.
THIS is the fundamental problem with static metadata. You can have an entire moving take place at night or in the dark and the final scene may be in daylight. That static metadata is going to report the daylight scene.

I am of the opinion that no metadata is better than static metadata on a disc.

In addition, the metadata always reports the theoretical color primaries and not the actual color primaries of the display used for grading. The good news is that this info does not appear to be used by any display, with our very limited testing.

I had a conversation with the colorist who has been working on HDR the longest and he said he would grade 100 nit cinema sized content MUCH differently than for the home on an 77" flat panel.

There are also at least two camps. Those that believe in a single master and those that don't. I am in the don't camp myself. Dolby Vision L2 and L8 trim pass metadata makes the single master approach more feasible, but I don't think they are perfect.
10:40 AM 09-26-2019
#513
sspears
Quote:
Originally Posted by Rolls-Royce
If you search online, you may be able to find something like a used Sencore, AVLab TPG by DVDO, or Accupel for a better price. They won't be cheap, but far less expensive than new. The issue then would be if CalMAN Home supports their use.

Addendum: I just checked. Surprise, surprise! CalMAN Home supports the Accupel line and the AVLab TPG.
I use an Accupel 6000 myself for analysis and when creating 1D and 3D LUTs. Analysis was the primary reason I purchased it though. The important thing is to make sure you are outputting the same format you are sending from your sources. Using CalMAN as an example, you can measure up to 10,000 points if you like. That is at least 10,000 different RGB windows. In reality, it can be much more since it is dynamic based on the display linearity. No test disc could ever have that many patterns. I consider the window patterns on any disc more for verification from our source.

The CalMAN lightening LUT is only ~100 patches that are fixed. Problem is, that only works on a display that is linear. When it works, it is fantastic and fast. I always use 10,000 points when I create 3D LUTs, which takes hours.

For a simple CMS or grayscale, discs cover that just fine since you just need 6 color patterns and 11-21 grayscale patterns.
10:45 AM 09-26-2019
#514
Dominic Chan
Quote:
Originally Posted by sspears
I am of the opinion that no metadata is better than static metadata on a disc.
Not sure if I understand this. Tone-mapping has to be based on something. The Panasonic UB820 player and the JVC 4K projectors, for example, assume 1000 nits if there’s no metadata. How can this be “better” than static metadata?
10:53 AM 09-26-2019
#515
sspears
Quote:
Originally Posted by Dominic Chan
Not sure if I understand this. Tone-mapping has to be based on something. The Panasonic UB820 player and the JVC 4K projectors, for example, assume 1000 nits if there’s no metadata. How can this be “better” than static metadata?
I believe dynamic metadata should be used such as Dolby Vision or HDR10+.

If you look at the sharpness pattern on the disc and switch between 600 and 10,000, on some displays that image gets very dark with 10,000. That pattern is the same pattern for all metadata levels, only the metadata is different. This is the danger of using static metadata to apply to the entire movie.

The same thing happens with the HDR10 10,000 vs. 1,000 montage. The 10,000 is really dark on many displays and it that is not the artistic intent.
11:48 AM 09-26-2019
#516
Rolls-Royce
Quote:
Originally Posted by sspears
I use an Accupel 6000 myself for analysis and when creating 1D and 3D LUTs. Analysis was the primary reason I purchased it though. The important thing is to make sure you are outputting the same format you are sending from your sources. Using CalMAN as an example, you can measure up to 10,000 points if you like. That is at least 10,000 different RGB windows. In reality, it can be much more since it is dynamic based on the display linearity. No test disc could ever have that many patterns. I consider the window patterns on any disc more for verification from our source.

The CalMAN lightening LUT is only ~100 patches that are fixed. Problem is, that only works on a display that is linear. When it works, it is fantastic and fast. I always use 10,000 points when I create 3D LUTs, which takes hours.

For a simple CMS or grayscale, discs cover that just fine since you just need 6 color patterns and 11-21 grayscale patterns.
I agree wholeheartedly with all your points, Stacy. I think CalMAN contains caveats about using the Lightning LUT that say essentially the same thing.

The correct gray scale measurement points are continuing to be a moving target for HDR, and now possibly for SDR based on some comments in another thread. I anticipate that pattern generators, with their flexibility to generate patterns on demand, will be the only viable way forward for calibration in the future. Except for verification purposes, "calibration discs" as we now know them will likely go the way of the dodo.
08:00 AM 09-28-2019
#517
sspears
Quote:
Originally Posted by DavidinGA
So essentially, that is no this calibration disc is not really intended for use on low nit projectors?
I spoke with Kris Deering and we will be adding a 350 nit version for projectors when we do the add-on next year.
08:06 AM 09-28-2019
#518
DavidinGA
Quote:
Originally Posted by sspears
I spoke with Kris Deering and we will be adding a 350 nit version for projectors when we do the add-on next year.
Thanks for the update.

Sent from my Pixel 2 XL using Tapatalk
06:14 PM 09-30-2019
#519
brygalt_hdr
Here are some suggestions for a disc update:

1) When viewing a pattern that exists on the disc in SDR and HDR (Color Tone for example), the currently unused down arrow on the remote could toggle between SDR and my selected HDR configuration for comparisons. I know it will take a second or two for the TV to switch over, that's fine.

2) Metadata sweeps: In DV and HDR10+ put an image or pattern on the screen and sweep each of the relevant metadata parameters like MaxFALL, MaxCLL, MaxDML, the color primaries, and if there are any others that make sense. Be sure to indicate the numeric value of the parameter as it sweeps in the lower right hand corner so I can correlate the value to what I am seeing on the screen.
07:21 AM 10-01-2019
#520
sspears
Quote:
Originally Posted by brygalt_hdr
Here are some suggestions for a disc update:

1) When viewing a pattern that exists on the disc in SDR and HDR (Color Tone for example), the currently unused down arrow on the remote could toggle between SDR and my selected HDR configuration for comparisons. I know it will take a second or two for the TV to switch over, that's fine.

2) Metadata sweeps: In DV and HDR10+ put an image or pattern on the screen and sweep each of the relevant metadata parameters like MaxFALL, MaxCLL, MaxDML, the color primaries, and if there are any others that make sense. Be sure to indicate the numeric value of the parameter as it sweeps in the lower right hand corner so I can correlate the value to what I am seeing on the screen.
Thank you for the suggestions.

Number 1 might be possible. We were not planning to do that, but we will consider it.

Number 2 may have a similar mode change to number 1. You can't change MaxCLL, MaxFALL or any of the static metadata within a single clip or even within a title on BD. They will have to be different clips in different titles. Every clip in a title will inherent the metadata of the first clip.
06:13 PM 10-01-2019
#521
brygalt_hdr
Quote:
Originally Posted by sspears
Thank you for the suggestions.

Number 1 might be possible. We were not planning to do that, but we will consider it.

Number 2 may have a similar mode change to number 1. You can't change MaxCLL, MaxFALL or any of the static metadata within a single clip or even within a title on BD. They will have to be different clips in different titles. Every clip in a title will inherent the metadata of the first clip.
Stacey,
Thanks for the quick reply. I probably just don't understand all of the mechanics of HDR metadata. From your reply I infer that the Max... parameters do not change, even in DV and HDR10+, and the dynamic metadata is contained in some other parameters to tell the display how to adjust the tone mapping and color mapping.

What I was trying to communicate in the second suggestion was to sweep the Dynamic metadata in DV and HDR10+. Whether or not this would be useful or just a novelty I'm not sure.

I have been enjoying the UHD benchmark disc for about a week or so, I'll post some of my observations at a later date.
06:32 PM 10-01-2019
#522
sspears
Quote:
Originally Posted by brygalt_hdr
Stacey,
Thanks for the quick reply. I probably just don't understand all of the mechanics of HDR metadata. From your reply I infer that the Max... parameters do not change, even in DV and HDR10+, and the dynamic metadata is contained in some other parameters to tell the display how to adjust the tone mapping and color mapping.

What I was trying to communicate in the second suggestion was to sweep the Dynamic metadata in DV and HDR10+. Whether or not this would be useful or just a novelty I'm not sure.

I have been enjoying the UHD benchmark disc for about a week or so, I'll post some of my observations at a later date.
You can do this today manually by using the configuration menu to change the nit level or by pressing the up arrow when a pattern is displayed. e.g. Select the sharpness pattern and then press up arrow and change from 600-10,000. On some displays, there will be no difference, which is good. The pattern is the same at all nit levels. On other displays, the image will get darker and darker as the nit level goes up.

On some players, like the XBOX ONE S/X, the image goes black when changing nit levels. Most players don't exhibit this behavior.

If you have any questions about any of the patterns, please don't hesitate to ask.
07:35 AM 10-02-2019
#523
Oscarilbo
Hi guys. I just order the calibration disc. Just a quick question:
I'm using the BenQ HT2550M and using the SmartECO lamp mode, which optimize contrast according to whatever is onscreen in order to save lamp life (which is the ultimate purpose). Not just that but BenQ and Experts agree that it gives the better overall picture quality.

Anyway, so by reading the "getting started" guidelines I guess I should deactivate this lamp mode and use just the Standard one while I do the whole calibration process. But my question is, after finish the calibration, what then? Can I go back to the SmartECO mode of the lamp?

Thank you so much in advance.
08:16 AM 10-02-2019
#524
sspears
Quote:
Originally Posted by Oscarilbo
Hi guys. I just order the calibration disc. Just a quick question:
I'm using the BenQ HT2550M and using the SmartECO lamp mode, which optimize contrast according to whatever is onscreen in order to save lamp life (which is the ultimate purpose). Not just that but BenQ and Experts agree that it gives the better overall picture quality.

Anyway, so by reading the "getting started" guidelines I guess I should deactivate this lamp mode and use just the Standard one while I do the whole calibration process. But my question is, after finish the calibration, what then? Can I go back to the SmartECO mode of the lamp?

Thank you so much in advance.
I don't have any experience with that lamp mode or projector, but normally I would use the same lamp mode for calibration that you use for viewing.
08:50 AM 10-02-2019
#525
Oscarilbo
Quote:
Originally Posted by sspears
I don't have any experience with that lamp mode or projector, but normally I would use the same lamp mode for calibration that you use for viewing.
Oh perfect, that's what I was thinking too. Thanks so much!
12:13 PM 10-02-2019
#526
Oscarilbo
Pardon my ignorance, but in the Configuration menu, how could I learn what Luminance (cd/m2) has and the HDR Gamut?
Thank you in advance.
01:42 PM 10-02-2019
#527
DavidinGA
Anyone have any before and after images to show how much improvement you gained through calibrating?



Thanks
:cool:
08:58 AM 10-03-2019
#528
sspears
Quote:
Originally Posted by Oscarilbo
Pardon my ignorance, but in the Configuration menu, how could I learn what Luminance (cd/m2) has and the HDR Gamut?
Thank you in advance.
I am not 100% sure what you are asking. Can you clarify?

The cd/m² is the metadata value used for MaxCLL and Max Mastering Display luminance. For some patterns, that also limits the peak value in that pattern. e.g. The contrast pattern for 1000 cd/m² goes up to code value 722 in the blinking boxes, with the background behind the boxes being 723. Code value 723 is 1000 nits in white. The 10,000 version goes to code value 939 in the blinking boxes with a background of 940, which is 10,000 in white.

1000 is what most will use for calibration. Content is mastered at various nit levels, but 1000 and 4000 are the most common. The idea is you would use the nit value closest to your displays capability to calibrate. Then the others are there to see how your display will handle content at those levels. For most displays today, 1000 is a good starting point, which is why it is the default. Then use 4000 to see how your display handle content at 4000 nits? Sony and WB has a lot of content mastered at 4000.

The gamut option applies to the saturation sweep ramps, saturation sweep windows and gamut window patterns. e.g. Green for P3D65 is the x,y coordinate of green in P3, which is inside of 2020 vs. 2020 green, which is in a different location. Basically P3D65 is inside of 2020. Most grading displays don't cover much beyond P3, so most content is P3 inside of D65.
09:21 AM 10-03-2019
#529
Oscarilbo
Quote:
Originally Posted by sspears
I am not 100% sure what you are asking. Can you clarify?

The cd/m² is the metadata value used for MaxCLL and Max Mastering Display luminance. For some patterns, that also limits the peak value in that pattern. e.g. The contrast pattern for 1000 cd/m² goes up to code value 722 in the blinking boxes, with the background behind the boxes being 723. Code value 723 is 1000 nits in white. The 10,000 version goes to code value 939 in the blinking boxes with a background of 940, which is 10,000 in white.

1000 is what most will use for calibration. Content is mastered at various nit levels, but 1000 and 4000 are the most common. The idea is you would use the nit value closest to your displays capability to calibrate. Then the others are there to see how your display will handle content at those levels. For most displays today, 1000 is a good starting point, which is why it is the default. Then use 4000 to see how your display handle content at 4000 nits? Sony and WB has a lot of content mastered at 4000.

The gamut option applies to the saturation sweep ramps, saturation sweep windows and gamut window patterns. e.g. Green for P3D65 is the x,y coordinate of green in P3, which is inside of 2020 vs. 2020 green, which is in a different location. Basically P3D65 is inside of 2020. Most grading displays don't cover much beyond P3, so most content is P3 inside of D65.
Oh Sorry.... my bad, I just read what I wrote and makes no sense. Yes, Thank you, I was referring to the first submenu option of the disc, Configuration, which asks about Luminance and HDR Gamut, and I was asking how can I measure my Projector capabilities in that regard. The Projector's user manual states it works under the REC.709 standard but doesn't mention specifically is SDR or HDR. Or maybe it's me who doesn't know how to interpret these qualities. Thanks so much.
10:13 AM 10-03-2019
#530
sspears
Quote:
Originally Posted by Oscarilbo
Oh Sorry.... my bad, I just read what I wrote and makes no sense. Yes, Thank you, I was referring to the first submenu option of the disc, Configuration, which asks about Luminance and HDR Gamut, and I was asking how can I measure my Projector capabilities in that regard. The Projector's user manual states it works under the REC.709 standard but doesn't mention specifically is SDR or HDR. Or maybe it's me who doesn't know how to interpret these qualities. Thanks so much.
709 is most commonly used for SDR.
05:10 PM 10-03-2019
#531
mrtickleuk
Quote:
Originally Posted by sspears
The gamut option applies to the saturation sweep ramps, saturation sweep windows and gamut window patterns. e.g. Green for P3D65 is the x,y coordinate of green in P3, which is inside of 2020 vs. 2020 green, which is in a different location. Basically P3D65 is inside of 2020. Most grading displays don't cover much beyond P3, so most content is P3 inside of D65.
I know you say "most" and this is true but it's also important not to get trapped into a "habit" of only looking at P3 and especially only calibrating to P3 (Calman defaults), otherwise it will become a de facto "limit" before we've even got off the ground. I'm actually quite worried about it. This is the second down-grade of HDR which I fear. (The other one was Dolby Vision content in Profile 4 being restricted to only having a Minimum Enhancement Layer. If I understand it right, it means that if no-one can use Profile 4 with a FEL because of these new devices that can't handle it, that means no more 12bit Dolby Vision on streaming, ever)

Twice this week I've seen discussions about how much content we have which is outwith P3 but inside rec.2020. The first was Vincent's excellent video:
https://www.youtube.com/watch?v=0XTgz5Z1bhE

The second was Tedd's post here, today.

ps. Apologies for the small hijack based on your single word "most" but I was interested in what you and others thing about the dangers of HDR being watered down in these ways so early in its life?
05:29 PM 10-03-2019
#532
Dominic Chan
Quote:
Originally Posted by mrtickleuk
I know you say "most" and this is true but it's also important not to get trapped into a "habit" of only looking at P3 and especially only calibrating to P3 (Calman defaults), otherwise it will become a de facto "limit" before we've even got off the ground. I'm actually quite worried about it. This is the second down-grade of HDR which I fear.
If you calibrate to BT.2020/P3 (P3 in BT.2020 container) you are simply “aligning” these points; you won’t be clipping colours outside the P3 gamut.
01:58 AM 10-04-2019
#533
Light Illusion
The reality is all grading displays are P3, because they have to be calibrated to some colour space... and calibrating to Rec2020 presently makes no sense.

That may change in the future.

The 'outside P3' colours supposedly found in Vincent's video are false colours, caused by the Blu-ray mastering process.
The original grading for all the films mentioned was P3 (I've checked).

Animation nearly always has such colour errors, as the colours used tend to be artificially close to the P3 gamut edge.
This cause artefacts, such as 'ringing', that cause the Blu-ray mastering to push the colours 'slightly' beyond the original mastered colour.

The colour only has to be one bit over for a display's 'out of gamut' warning signal to be activated.

You can actually do the same thing with LightSpace, and generate an Out Of Gamut LUT, to show colours that are beyond a given colour space, or even beyond the colours a given display can show correctly.

Steve

Edit to add: Oh - I should add that one of the reasons all HDR grading is P3 is because digital cinema projection is presently P3, so again no point grading beyond P3 - at this moment in time.
03:15 AM 10-04-2019
#534
ConnecTEDDD
Quote:
Originally Posted by sspears
I use an Accupel 6000 myself for analysis and when creating 1D and 3D LUTs.
Hi Stacey,

Have you seen a strange flickering to the screen when the Accupel 6000 generates patterns with all versions of CalMAN, including the 2019 R2 also?

Its a very noticed flickering.

Accupel API has 2 commands to generate patterns.

1) Fast Method: to update the whole new patch RGB-triplet values at once, with one command.

2) Slow Method: to update each one channel separatelly, for example if you last pattern had RGB-Triplet 200.100.50 and the next one was 150.150.150, software will have to send 3 commands, to update each colorchannel, so a flicker will appear, as you ask from generator to generate 3 patches (to each of 3 sub-pixels), to able to generate at the end the new RGB-Triplet you want.

The problem doing that approach is that the generator becomes about 2 or more times slower vs. the Murideo Six-G for example, when you will use it with CalMAN. Also the flickering is not good for the display you measure as its not helping for stabilize.

This flickering due to the way CalMAN is operating the Accupel 6000 is affecting only CalMAN users, as ChromaPure and LightSpace are using the 'Fast Method', and there no flickering when you will use Accupel 6000 with ChromaPure or LightSpace, and the patch generation speed patch the speed of Murideo Six-G.

That issue of Accupel with CalMAN has been reported already before 2 years to SpectraCAL, and I have personally informed Tom Huffman (responsible for Accupel generators) before at least one year.

That 'slow' way of operating the pattern generator is increasing your total profiling time when you perform 10000 point 3D LUT profiling, at least 30min you loose compared with Murideo for example with CalMAN.

Quote:
Originally Posted by sspears
Using CalMAN as an example, you can measure up to 10,000 points if you like. That is at least 10,000 different RGB windows. In reality, it can be much more since it is dynamic based on the display linearity. No test disc could ever have that many patterns. I consider the window patterns on any disc more for verification from our source.
Actually Ted's calibration disk, which has been released at 2013 do this :)



You can load the disk to your player, like an OPPO for example, and select the 21-Point Cube 1 sec DIP mode chapter which will display 9261 patches (it will display each patch per 1 second), without any user prompt during the whole process except one initial press 'OK' for starting measurements with LightSpace.

That '1 sec' chapter will work only Klein K-10A colorimeter as the meter is so fast and has fixed integration time (it takes about 150ms to read any patch), it will take 2H34M to finish all the automatic measurements of 9261 patches.

While that chapter will change the patterns per 1 second, it will include 0.5 sec of delay before the meter reading, for the patch to stabilize to the screen. That method of special syncing I have designed the disk is working only with LightSpace.

Just I wanted to remind that capabilities, as exist calibration disk to take 1000/4913/9261 colors without any manual process of changing patches, I post this info here as you have posted that its impossible to be displayed 10000 patterns via a disk. we talked about that capability again before 4 years: https://www.avsforum.com/forum/139-d...l#post37413562

Actually that process is faster than from performing the same measurements using an external generator, like Murideo for example, as if you measure the same patches (9261 colors) with 0.5 sec delay before patch read, it will take up to about 5-7 minutes longer, as you add latency and time it will spend for software to send commands and communicate with the external generator, for the patterns to be generated.

So that method is actually faster than from using any external generator.
04:01 AM 10-04-2019
#535
ConnecTEDDD
Quote:
Originally Posted by mrtickleuk
I know you say "most" and this is true but it's also important not to get trapped into a "habit" of only looking at P3 and especially only calibrating to P3 (Calman defaults), otherwise it will become a de facto "limit" before we've even got off the ground. I'm actually quite worried about it. This is the second down-grade of HDR which I fear. (The other one was Dolby Vision content in Profile 4 being restricted to only having a Minimum Enhancement Layer. If I understand it right, it means that if no-one can use Profile 4 with a FEL because of these new devices that can't handle it, that means no more 12bit Dolby Vision on streaming, ever)

Twice this week I've seen discussions about how much content we have which is outwith P3 but inside rec.2020. The first was Vincent's excellent video:
https://www.youtube.com/watch?v=0XTgz5Z1bhE

The second was Tedd's post here, today.
The reality is that the actual problem is even bigger, I have posted before 2 years (text below THX pictures...click the 3 links): https://www.avsforum.com/forum/139-d...l#post53757713

My post will disappoint a lot who have entered to HDR calibration marathon, trying to calibrate for HDR with any possible way, the fact that we are all limited from the big problem appear from REC.2020 YCbCr encoding. :(

Its impossible to watch any HDR content as its mastered, even if you buy the a Sony BMV-X300 to your home, the same monitor a an HDR movie has been mastered, you know why? ....because colorist do the grading in uncompressed RGB but later once the movie will be encoded to YCbCr, there issue with REC20202 YCbCr compressing which will add errors between 3.2 to 6.3 dE 2000 range!

So if you look the same movie to 2x Sony BVM-X300 mastering monitor, one will play the RGB version and the other the disk version from OPPO for example, they will not look the same.

Stacey, have you performed that test with your reference source material? ...as you can have access for such kind of tests? to compare uncompressed version of Montage vs. the disk Montage content?

So starting from that fact, you will never see an HDR movie as its been mastered.

The problem is so large and there still no complete solution, BTW with SDR YCbCr REC.709 i didn't had such problem.

Even the Sony BVX-300 monitors (50K$) they use for the most HDR/DV mastering has ABL, as it can do about 1100 nits window and 170 nits full field white, just industry ignore that detail (while the specs for Grade 1 monitor say that the mastering monitor should not have any form or power limiting / ABL circuit enabled and should display the same nits to any size of window.), just whole industry is ingoring that detail as it was not available since the arrival of dual-lcd Sony/FSI other display for HDR mastering to buy, as Dolby can only loan the very limited in number Dolby Pulsar monitors.

You can't perform color grading of a movie well when the display has ABL limiters and thermal issues, like the Sony which enabling protection and reduce peak when it will reach some specific temperature the sensors it has to protect panel/electronics.

The same is required during playback, all OLED's are super unstable during playback of HDR10 content, even with same APL, you can have +-200 nits difference over the time.

So the whole HDR calibration concept is lucking hen its coming to color accuracy, with current display tech to consumer market.

+ add to all these problems the color volume issues of OLED in HDR mode due to w-subpixel, + the tone mapping which alter the artistic intent as it will deviate from standard of PQ-EOTF tracking...(as post-production monitors just clip, not tone-map)

To watch a movie as its been mastered, any display should not have any kind of tone mapping, all these should be disabled if you want to watch a movie as its mastered. (if they fix the problem with compression first)

Dolby Vision (disk releases) second stream layer of 1080p (which is now is YCbCr 4:2:0 now.....YCbCr 4:2:2 in the future) .... that DV layer basically is just the difference between 10bit and 12bit...so the playback device use the 2 layers (+ dynamic metadata) to combine and create a 12-bit signal as Dolby has found that to avoiding banding in the PQ transfer functions you need 11 bits when you are using YCbCr sub-sampling, so with 12bit signal at the end it will have better gradation.

So even DV releases at disk are affected from YCbCr REC.2020 compression problem.

Dolby comes to reduce the encoding errors with ICtCp,

To have a complete ICtCp, they have to be release in market disks only with DV version of the movie, which I found very difficult because it will sell only a few compared to HDR10/DV release. (a lot of companies have exit disk player market, like OPPO, Samsung)

According to Dolby ICtCp is better, but there experiments where they have found weaknesses also, the group called ''Joint Collaborative Team on Video Coding (JCTVC)'' has performed some testing comparing non constant or constant luminance YCbCr vs. ICtCp, as YCbCr has better coverage of pure colors close to edge of the 2020 gamut (Reference: Joint Collaborative Team on Video Coding (JCTVC-X0051) - ICtCp colour representation - Observations & Findings), so ICtCp is not clearly better to all areas.

With streaming of DV, sure it's encoded using ICtCp because it's native DV delivery format, they have no reason to deliver with YCbCr.

https://www.smpte.org/sites/default/...ce_Pytlarz.pdf

So out of gamut colors as Vincent talking to his video have introduced after the encoding, as when you map P3 inside 2020 container, all colors should be inside P3 colorspace only, before the YCbCr encoding.
04:11 AM 10-04-2019
#536
ConnecTEDDD
Stacey,

It will be interesting to release in the future the 'Montage' as DoVi MP4 media file encoded with ICtCp.
07:41 AM 10-04-2019
#537
mombasa123
Quote:
Originally Posted by Light Illusion
The reality is all grading displays are P3, because they have to be calibrated to some colour space... and calibrating to Rec2020 presently makes no sense.

That may change in the future.

The 'outside P3' colours supposedly found in Vincent's video are false colours, caused by the Blu-ray mastering process.
The original grading for all the films mentioned was P3 (I've checked).

Animation nearly always has such colour errors, as the colours used tend to be artificially close to the P3 gamut edge.
This cause artefacts, such as 'ringing', that cause the Blu-ray mastering to push the colours 'slightly' beyond the original mastered colour.

The colour only has to be one bit over for a display's 'out of gamut' warning signal to be activated.

You can actually do the same thing with LightSpace, and generate an Out Of Gamut LUT, to show colours that are beyond a given colour space, or even beyond the colours a given display can show correctly.

Steve

Edit to add: Oh - I should add that one of the reasons all HDR grading is P3 is because digital cinema projection is presently P3, so again no point grading beyond P3 - at this moment in time.
Very useful info!
08:08 AM 10-04-2019
#538
sspears
Quote:
Originally Posted by ConnecTEDDD
Hi Stacey,

Have you seen a strange flickering to the screen when the Accupel 6000 generates patterns with all versions of CalMAN, including the 2019 R2 also?

Its a very noticed flickering.

Accupel API has 2 commands to generate patterns.

1) Fast Method: to update the whole new patch RGB-triplet values at once, with one command.

2) Slow Method: to update each one channel separatelly, for example if you last pattern had RGB-Triplet 200.100.50 and the next one was 150.150.150, software will have to send 3 commands, to update each colorchannel, so a flicker will appear, as you ask from generator to generate 3 patches (to each of 3 sub-pixels), to able to generate at the end the new RGB-Triplet you want.

The problem doing that approach is that the generator becomes about 2 or more times slower vs. the Murideo Six-G for example, when you will use it with CalMAN. Also the flickering is not good for the display you measure as its not helping for stabilize.

This flickering due to the way CalMAN is operating the Accupel 6000 is affecting only CalMAN users, as ChromaPure and LightSpace are using the 'Fast Method', and there no flickering when you will use Accupel 6000 with ChromaPure or LightSpace, and the patch generation speed patch the speed of Murideo Six-G.

That issue of Accupel with CalMAN has been reported already before 2 years to SpectraCAL, and I have personally informed Tom Huffman (responsible for Accupel generators) before at least one year.

That 'slow' way of operating the pattern generator is increasing your total profiling time when you perform 10000 point 3D LUT profiling, at least 30min you loose compared with Murideo for example with CalMAN.
Sounds like something Portrait should look at.
08:17 AM 10-04-2019
#539
sspears
Quote:
Originally Posted by ConnecTEDDD
The reality is that the actual problem is even bigger, I have posted before 2 years (text below THX pictures...click the 3 links): https://www.avsforum.com/forum/139-d...l#post53757713

My post will disappoint a lot who have entered to HDR calibration marathon, trying to calibrate for HDR with any possible way, the fact that we are all limited from the big problem appear from REC.2020 YCbCr encoding. :(

Its impossible to watch any HDR content as its mastered, even if you buy the a Sony BMV-X300 to your home, the same monitor a an HDR movie has been mastered, you know why? ....because colorist do the grading in uncompressed RGB but later once the movie will be encoded to YCbCr, there issue with REC20202 YCbCr compressing which will add errors between 3.2 to 6.3 dE 2000 range!

So if you look the same movie to 2x Sony BVM-X300 mastering monitor, one will play the RGB version and the other the disk version from OPPO for example, they will not look the same.

Stacey, have you performed that test with your reference source material? ...as you can have access for such kind of tests? to compare uncompressed version of Montage vs. the disk Montage content?

So starting from that fact, you will never see an HDR movie as its been mastered.

The problem is so large and there still no complete solution, BTW with SDR YCbCr REC.709 i didn't had such problem.

Even the Sony BVX-300 monitors (50K$) they use for the most HDR/DV mastering has ABL, as it can do about 1100 nits window and 170 nits full field white, just industry ignore that detail (while the specs for Grade 1 monitor say that the mastering monitor should not have any form or power limiting / ABL circuit enabled and should display the same nits to any size of window.), just whole industry is ingoring that detail as it was not available since the arrival of dual-lcd Sony/FSI other display for HDR mastering to buy, as Dolby can only loan the very limited in number Dolby Pulsar monitors.

You can't perform color grading of a movie well when the display has ABL limiters and thermal issues, like the Sony which enabling protection and reduce peak when it will reach some specific temperature the sensors it has to protect panel/electronics.

The same is required during playback, all OLED's are super unstable during playback of HDR10 content, even with same APL, you can have +-200 nits difference over the time.

So the whole HDR calibration concept is lucking hen its coming to color accuracy, with current display tech to consumer market.

+ add to all these problems the color volume issues of OLED in HDR mode due to w-subpixel, + the tone mapping which alter the artistic intent as it will deviate from standard of PQ-EOTF tracking...(as post-production monitors just clip, not tone-map)

To watch a movie as its been mastered, any display should not have any kind of tone mapping, all these should be disabled if you want to watch a movie as its mastered. (if they fix the problem with compression first)

Dolby Vision (disk releases) second stream layer of 1080p (which is now is YCbCr 4:2:0 now.....YCbCr 4:2:2 in the future) .... that DV layer basically is just the difference between 10bit and 12bit...so the playback device use the 2 layers (+ dynamic metadata) to combine and create a 12-bit signal as Dolby has found that to avoiding banding in the PQ transfer functions you need 11 bits when you are using YCbCr sub-sampling, so with 12bit signal at the end it will have better gradation.

So even DV releases at disk are affected from YCbCr REC.2020 compression problem.

Dolby comes to reduce the encoding errors with ICtCp,

To have a complete ICtCp, they have to be release in market disks only with DV version of the movie, which I found very difficult because it will sell only a few compared to HDR10/DV release. (a lot of companies have exit disk player market, like OPPO, Samsung)

According to Dolby ICtCp is better, but there experiments where they have found weaknesses also, the group called ''Joint Collaborative Team on Video Coding (JCTVC)'' has performed some testing comparing non constant or constant luminance YCbCr vs. ICtCp, as YCbCr has better coverage of pure colors close to edge of the 2020 gamut (Reference: Joint Collaborative Team on Video Coding (JCTVC-X0051) - ICtCp colour representation - Observations & Findings), so ICtCp is not clearly better to all areas.

With streaming of DV, sure it's encoded using ICtCp because it's native DV delivery format, they have no reason to deliver with YCbCr.

https://www.smpte.org/sites/default/...ce_Pytlarz.pdf

So out of gamut colors as Vincent talking to his video have introduced after the encoding, as when you map P3 inside 2020 container, all colors should be inside P3 colorspace only, before the YCbCr encoding.
We did not grade in P3, we graded in 2020 on the Pulsar. The PRM was used for the 100 and 600 nit trim passes. While the color volume was not much bigger than P3, all the x,y values are 2020, so no conversion from P3 into 2020 was needed. That was one of our three goals. The other two were staying at 8KHD until encoding and going up to 10,000 nits. And we were able to do all three. Now we did have some Resolve related issues that will be fixed in the future when we do the Dolby Vision 4.0 grade.

The Pulsar was around 3000 nits full screen white. The horse in snow shot has an APL of around 1000 and peaks at 6000. When we include the HDR Analyzer montage next time, you will be able to see the levels and gamut of every frame play in realtime. its really cool to see, if you are into that sort of thing. :)

I have also seen the 1000 nit version on the X300 and X310. We ran the montage through Transkoder first, which fixes a lot of the YCbCr issues you mention, so the disc looks very much like the master in RGB. ICtCp would improve what you hare discussing. Before Transkoder, the red cactus had some noise issues from YCbCr. After Transkoder, they were mostly gone. Same for the red tulips and strawberries. Saturated reds are were most of the YCbCr artifacts show up with HDR. There are some purples that should be blue, but that was a Resolve clipping the gamut at the 2020 boundary (content went beyond 2020 since the camera's spectral response is larger than 2020.)

The DV enhancement layer is actually more than just the difference between 10 and 12-bit. It is the difference between the decoded 10-bit 4:2:0 base layer and the original 12-bit 4:2:2 source. So if there are compression artifacts in the base layer, those can actually get fixed up when the enhancement layer is applied.

When LG did their 8K launch event a couple of weeks ago, in the US, they had both an mp4 8K HD encode as well as the 16-bit TIFFs. From what I have heard, it was difficult to tell the difference. I was worried the 60a/99p would be too low for 8KHD. I did end up using placebo mode, which took a while to encode. The UHD version takes around 12 hours to encode at the slow setting. The DV versions due have compression artifacts because the Sony encoder is not as good as x265. You have to pixel peep to see the difference, but they are there. Now I can use x265 for Dolby Vision 4.0 profile 7, so that will be a better encode too. I will also use placebo next time around.
08:27 AM 10-04-2019
#540
sspears
Quote:
Originally Posted by mrtickleuk
I know you say "most" and this is true but it's also important not to get trapped into a "habit" of only looking at P3 and especially only calibrating to P3 (Calman defaults), otherwise it will become a de facto "limit" before we've even got off the ground. I'm actually quite worried about it. This is the second down-grade of HDR which I fear. (The other one was Dolby Vision content in Profile 4 being restricted to only having a Minimum Enhancement Layer. If I understand it right, it means that if no-one can use Profile 4 with a FEL because of these new devices that can't handle it, that means no more 12bit Dolby Vision on streaming, ever)

Twice this week I've seen discussions about how much content we have which is outwith P3 but inside rec.2020. The first was Vincent's excellent video:
https://www.youtube.com/watch?v=0XTgz5Z1bhE

The second was Tedd's post here, today.

ps. Apologies for the small hijack based on your single word "most" but I was interested in what you and others thing about the dangers of HDR being watered down in these ways so early in its life?
I don't consider HDR being watered down from that standpoint. There are some that are being very conservative with the grade as they worry about making the viewer uncomfortable. This will change over time as the clients gets more comfortable with HDR.

The issue is the gamut of displays like the X300, X310, etc... are they don't cover much beyond P3. They don't fully cover P3 either. I think they are rated at 99% P3. In 2020 mode, some areas are beyond P3, while some are less. Most grade this way, we chose to put the display into 2020 mode vs. P3 mode to avoid the later conversion into 2020.

Pixar's Inside Out does have colors beyond 2020 that are intentional. The red clown is a great example that has 2020 reds. It also has a shot that goes to 10,000 nits. Both were used as a creative tool. Theatrically, in Dolby Cinema, you could see the true red color.