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Old 3rd February 2019, 14:28   #54561  |  Link
tp4tissue
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Originally Posted by Warner306 View Post
I don't think this is intended, but it could be doing some monkey business with the source, or you need an HDR calibration. Like I said, the newer the model, the better. Panasonic and Sony are known to be better at this.
Is there a way to calibrate through madtpg for use with the HDR tone-mapping function ?

I noticed going through dispcal, the calibration for rec2020 will not slot into the normal calibration page, and only works for the hdr tone-map page.
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Old 3rd February 2019, 17:23   #54562  |  Link
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Originally Posted by Alexkral View Post
A final issue with a lot of displays, specifically home TVs, is the manufacturers deliberately deviating from the HDR specification, in an attempt to generate what they view as 'better' images.

Many home TV manufacturers therefore deliberately 'distort' the PQ HDR EOTF (gamma curve) to attempt to overcome this issue.

https://www.lightillusion.com/uhdtv.html
This is one of the early articles released when HDR was introduced. I think it is less common to artificially brighten HDR content since calibrators have made TV manufacturers more conscious of properly following the PQ curve. Consumers are also becoming more educated about PQ HDR content.

Brightening the PQ curve does come with drawbacks. All HDR video games include a brightness slider to increase the brightness of HDR games. However, this raises the value for reference white, which comes at the expense of making the blacks more grey in dark scenes. The 2017 LG OLEDs suffered from this issue, which was corrected in the 2018 models. I don't know if the 2018 models are doing any other manipulation of the PQ curve, but it doesn't really make sense to have a dynamic tone curve that is constantly fluctuating above and below the PQ curve without distorting the image. Samsung uses a static curve with its QLEDs, but it is either rising from black more slowly or compensating for the brighter 0-100 nits by using more aggressive local dimming. I'm sure even Samsung will do away with this when dynamic tone mapping is added.

You don't really want to brighten images with absolute brightness values because the image can become washed out if pushed too far.

Last edited by Warner306; 3rd February 2019 at 17:28.
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Old 3rd February 2019, 17:27   #54563  |  Link
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Originally Posted by tp4tissue View Post
Is there a way to calibrate through madtpg for use with the HDR tone-mapping function ?

I noticed going through dispcal, the calibration for rec2020 will not slot into the normal calibration page, and only works for the hdr tone-map page.
You can create an SDR 3D LUT if you output in an SDR format. But you can't use a 3D LUT with pixel shader when outputting in an HDR format. You would have to choose to tone map by 3D LUT and make a few static tone curves: 500 nits, 1,000 nits, 1,500 nits and 4,000 nits to replace the display's internal static curves. This could be accomplished with a few profile rules under hdr.
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Old 3rd February 2019, 19:09   #54564  |  Link
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Hi folks,
Will madvr support HDR10+ dynamic metadata decode or passthrough?
Thanks
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Old 3rd February 2019, 22:05   #54565  |  Link
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Hi folks,
Will madvr support HDR10+ dynamic metadata decode or passthrough?
Thanks
That depends on LAV filters first.

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Originally Posted by Warner306 View Post
This is one of the early articles released when HDR was introduced.
The problem with HDR being too dark is still there though. 100 nits for diffuse white is too low in not ideal conditions (I'd say it's even too low in ideal conditions but that's just my oppinion) compared to where most people is used to see it in SDR. ITU-R BT.2408-0 recommends diffuse white = 203 nits for PQ and HLG production on a 1000 nits peak luminance display. Another study in the same report suggests diffuse white at 140 nits for indoor scenes and 425 nits for outdoor scenes, for PQ with 4000 nits peak luminance. I think I have read somewhere that at least some titles now are being graded with diffuse white at 203 nits. This should be the best way to solve this. We loose 1 stop at highlights but the overall brightness match better with SDR.

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it doesn't really make sense to have a dynamic tone curve that is constantly fluctuating above and below the PQ curve without distorting the image.
If I'm not wrong, both SMPTE ST 2094-10 (Dolby Vision) and SMPTE ST 2094-40 (HDR10+) curves change dynamically the knee point in a similar way that what Soulnight's utility with dynamic target nits is doing now with the BT.2390 EETF.

Last edited by Alexkral; 3rd February 2019 at 22:10.
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Old 3rd February 2019, 22:37   #54566  |  Link
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Quote:
Originally Posted by Warner306 View Post
You can create an SDR 3D LUT if you output in an SDR format. But you can't use a 3D LUT with pixel shader when outputting in an HDR format. You would have to choose to tone map by 3D LUT and make a few static tone curves: 500 nits, 1,000 nits, 1,500 nits and 4,000 nits to replace the display's internal static curves. This could be accomplished with a few profile rules under hdr.
Yea, that's what I meant, create an HDR 3Dlut, but ONTOP of Dynamic Tonemapping, output HDR.

Do you know if this feature will be added in the future ?

Seems to be straightforward, is there a specific hitch that it's not already possible ?
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Old 3rd February 2019, 23:05   #54567  |  Link
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Ive tried error diffusion 1 and 2 for dithering in madvr and I cant see any obvious differance between them. Im upscaling BDs to 4K and displaying on a large 145" curved screen with a JVC NX9 4K projector. Since I dont know which is best as I see nothing, which might be the prefered option in my case producing the less artifacts? Thanks in advance...
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Old 3rd February 2019, 23:08   #54568  |  Link
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the default ordered dithering
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Old 3rd February 2019, 23:39   #54569  |  Link
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the default ordered dithering
Can you explain to me please huhn why ordered dithering is better than error diffusion 1 & 2 please? Thank you kindly for helping...
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Old 4th February 2019, 00:05   #54570  |  Link
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He's not saying it is. But if you don't SEE a difference, there is a HUGE difference in performance between ordered and error diffusion and there's no sense killing performance for something you can't see.
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Old 4th February 2019, 00:09   #54571  |  Link
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He's not saying it is. But if you don't SEE a difference, there is a HUGE difference in performance between ordered and error diffusion and there's no sense killing performance for something you can't see.
Ok thank you I understand, however that isnt an issue with me anyway as I have the 1080Ti card and using the highest NGU settings upscaling everything to 4K. My rendering hardly ever goes above 20 and I have no dropped or repeated frames for days/ever.

Last edited by 70MM; 4th February 2019 at 00:13.
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Old 4th February 2019, 00:27   #54572  |  Link
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Ok thank you I understand, however that isnt an issue with me anyway as I have the 1080Ti card and using the highest NGU settings upscaling everything to 4K. My rendering hardly ever goes above 20 and I have no dropped or repeated frames for days/ever.
Luma scaler difference is the only thing that's visibly different (At a Distance).

For chroma, dithering, etc, the differences are really only visible if you walk in real close, or zoom in.


The sharpening algorithms are also very visible, but they're taste-based, and not a better or worse situation.


LOOKING FOR a difference is mostly academic, because you simply wouldn't notice much of it while a movie plays.

If knowing it's there helps you sleep at night or justify equipment purchases, then Zoom in, squint real hard, the little hairs on people's faces will look just a tad sharper.
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Old 4th February 2019, 01:12   #54573  |  Link
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thank you for the comments...
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Old 4th February 2019, 07:48   #54574  |  Link
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Can you explain to me please huhn why ordered dithering is better than error diffusion 1 & 2 please? Thank you kindly for helping...
Error diffusion is a tiny bit sharper and more random while ordered dithering has the lowest apparent noise. All three options are very good, I think I prefer ordered dithering on my 55" OLED TV while I like ED 1 or 2 on my LCD monitors, but the differences are also very subtle. Ordered is a great option because it is so high quality while also being fast.
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Old 4th February 2019, 16:47   #54575  |  Link
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Originally Posted by Alexkral View Post
The problem with HDR being too dark is still there though. 100 nits for diffuse white is too low in not ideal conditions (I'd say it's even too low in ideal conditions but that's just my oppinion) compared to where most people is used to see it in SDR. ITU-R BT.2408-0 recommends diffuse white = 203 nits for PQ and HLG production on a 1000 nits peak luminance display. Another study in the same report suggests diffuse white at 140 nits for indoor scenes and 425 nits for outdoor scenes, for PQ with 4000 nits peak luminance. I think I have read somewhere that at least some titles now are being graded with diffuse white at 203 nits. This should be the best way to solve this. We loose 1 stop at highlights but the overall brightness match better with SDR.
I wouldn't be against raising the value of reference white slightly for PQ HDR content. The problem is all existing HDR displays are tuned to tone map for a reference white of 100 nits, so I don't know how you would get around that without breaking support for all legacy HDR displays. I don't think HDR is too dark when viewed without ambient light in the room.

Displays could at least have a standard brightness slider like video games to make HDR a little brighter during the daytime, even if raised the bottom of the image a little.

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Originally Posted by Alexkral View Post
If I'm not wrong, both SMPTE ST 2094-10 (Dolby Vision) and SMPTE ST 2094-40 (HDR10+) curves change dynamically the knee point in a similar way that what Soulnight's utility with dynamic target nits is doing now with the BT.2390 EETF.
The knee point just changes where the tone mapping roll-off begins. The curve always slopes to the right away from the PQ curve, so the image never gets brighter; it only gets darker.

Soulnight's tool increases or decreases the target nits. Increasing the target nits raises the knee point further up the PQ curve to reduce compression, but it also changes the absolute brightness of all values relative to the output display. For example, if the display is 100 nits, selecting 200 nits will lead to a loss of more or less half of the calculated brightness of the tone mapped values because the target display is assumed to be twice as bright as the actual output display. The gamma curve is relative, so the output brightness isn't always that precise, but it is close.

When the target nits is higher, the pixel values are more spread out, but they use more of the lower region of the gamma curve to handle the majority of the pixels 0-100 nits. The pixels that represent the highlights are separated to the brightest end of the gamma curve. So the image has more contrast between bright and dark detail and looks less flat because the pixels are less compressed, but the overall image ends up darker.

Last edited by Warner306; 4th February 2019 at 16:49.
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Old 4th February 2019, 20:42   #54576  |  Link
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I wouldn't be against raising the value of reference white slightly for PQ HDR content. The problem is all existing HDR displays are tuned to tone map for a reference white of 100 nits, so I don't know how you would get around that without breaking support for all legacy HDR displays. I don't think HDR is too dark when viewed without ambient light in the room.

I noticed that calibrating to 2.2/2.4 (relative) gamma on LCD is much more similar in appearance to 2.2/2.4 (absolute) gamma (1886) on CRT/Plasma/OLED, vs using absolute gamma (1886) on LCD which makes everything greyish.

So, the near crush dark tones when using relative gamma on LCD is probably Correct. It's just more crush like in home environments where the room light is on.

The moral of the story is, it's suppose to look like that, just turn the lights off.
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Last edited by tp4tissue; 4th February 2019 at 20:46.
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Old 4th February 2019, 22:00   #54577  |  Link
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Shockingly 418.82 didn't break HDR switching. LOL
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Old 4th February 2019, 23:14   #54578  |  Link
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Weird Gamut behavior.

So on my ATI card, my spare bedroom tv reports a slightly wider Gamut +10% vs my Nvidia Card.

Is it because the Nvidia card is using the alpha channels differently ?

Does madvr use alpha channels in output or only 24bit.
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Old 4th February 2019, 23:16   #54579  |  Link
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There is no alpha channel on the output. Different results might be up to dithering.
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Old 4th February 2019, 23:33   #54580  |  Link
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There is no alpha channel on the output. Different results might be up to dithering.
Hrrrm..

I guess that must be the tv's gamut clamping software intervening with the nvidia output.

Is there a fundamental output difference between ATI and Nvidia, some sort of flags ??

Because both these cards are setup for 8bit rgb, yet the ATI results in the +10% , quite large a swing.
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