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Old 10th October 2018, 07:33   #61  |  Link
hydra3333
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Quote:
Originally Posted by videoh View Post
have to find a way to recruit more coders to make CUDA/CUDASynth filters
I may have a little time next year to begin looking at such things. It'll be a stretch for a bit, learning new concepts and languages and whatnot when my knowledge is old and dates back to the 70s/80s/90s and when Fortran and pdp/vax assembler were a thing
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Old 28th April 2019, 17:37   #62  |  Link
jackoneill
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Hi. Shouldn't the VapourSynth version set the frame properties _Matrix, _Transfer, and _Primaries? For example, ffms2 sets these properties when loading some HDR10 video:
_Matrix = 9 (BT.2020 NCL)
_Transfer = 16 (SMPTE 2084)
_Primaries = 9 (BT.2020)

These aren't correct for the output of DGHDRtoSDR, are they?
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Old 28th April 2019, 18:21   #63  |  Link
kolak
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Those are correct values for HDR10.
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Old 15th June 2019, 11:52   #64  |  Link
thecoreyburton
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How reliable are the default settings for doing a UHD > BD conversion?

I've only got access to SDR displays, but there are cases where the UHD master is significantly better than the BD master. I've begun doing a few tests before I tackle the bulk of the task and whilst a vast majority of the scenes look perfect, I've noticed a few things aren't how I'd expect here and there. In some cases, whites appear tinted green (slightly) and in others they appear blown out (but only slightly). This is complicated by the fact that the UHD masters I'm dealing with are different to the BD masters I'm comparing to, and they could very easily have had minor adjustments done to colors and luminescence prior to their release.

I've had very limited experience with HDR and I'm interested to know if the default settings are one-size-fits-all (and tweaking is typically for specific scenarios), or if there will be a lot of manual tweaking and subjective checking involved per-source.
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Old 15th June 2019, 12:27   #65  |  Link
gonca
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They are quite good.
Try it and let your eyes be the judge
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Old 15th June 2019, 17:18   #66  |  Link
thecoreyburton
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Thank you for the reply! That's sound advice, but my problem is that my eyes are noticing a few things that don't look right to me. Specifically, the handling of the brighter areas of the film (with whites appearing tinted or blown out in somewhat infrequent situations). For the most part everything looks right, but in certain environments (outdoor scenes, for instance), something looks a little off. I'm just unsure if this is a side effect of the HDR > SDR process, something that needs tweaking in the plugin settings or if it's a result of a different master being used and my perception's accustomed to the old one still (although this occurs across in most sources I've tried so far at one place or another).
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Old 15th June 2019, 18:17   #67  |  Link
videoh
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It's hard to respond to nebulous subjective observations. Can you post a link to a source sample and script that illustrates your issue? That would allow proper analysis.

HDR->SDR is going to involve some trade-offs. There is no theoretically "correct" way to do it.

Last edited by videoh; 15th June 2019 at 18:25.
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Old 15th June 2019, 18:30   #68  |  Link
videoh
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Quote:
Originally Posted by jackoneill View Post
Hi. Shouldn't the VapourSynth version set the frame properties _Matrix, _Transfer, and _Primaries? For example, ffms2 sets these properties when loading some HDR10 video:
_Matrix = 9 (BT.2020 NCL)
_Transfer = 16 (SMPTE 2084)
_Primaries = 9 (BT.2020)

These aren't correct for the output of DGHDRtoSDR, are they?
As you suggest, DGHDRtoSDR() should update the VapourSynth properties after converting to SDR 709 output. Thank you for reporting this deficiency, jackoneill.

Last edited by videoh; 15th June 2019 at 23:06.
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Old 16th June 2019, 09:16   #69  |  Link
thecoreyburton
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Thank you for the response! Sorry for being vague. I've found a source which I had available in both formats and have located a matching frame. Here's a visual comparison:

4KBD HDR > SDR:


BD SDR:


The sky appears to have a subtle green tint to it (though this could be my imagination, as a result of the other things I've noticed). The image appears to be desaturated. There's significantly less contrast, notably in the whites of the dog.

These observations all came from examining the 4KBD on it's own, with exception of the whites lacking contrast (which I originally thought was them being blown out). The 4KBD looks superior to me at first glance, but when focusing on the dog in comparison to the sky, things look off in some way. These observations are consistent with what I've seen in other sources too. Again, this is only for certain scenes and they are a definite minority overall.

The script I've used for this example isn't anything special:
Quote:
DGSource("test.dgi", FullDepth=True)
DGHDRToSDR()
Spline64Resize(1920, 1080)

Last edited by thecoreyburton; 16th June 2019 at 09:27.
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Old 16th June 2019, 11:17   #70  |  Link
ChaosKing
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Originally Posted by videoh View Post
As you suggest, DGHDRtoSDR() should update the VapourSynth properties after converting to SDR 709 output. Thank you for reporting this deficiency, jackoneill.
And maybe update the link on the first page or change it to http://rationalqm.us/hdr/
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Old 16th June 2019, 17:08   #71  |  Link
videoh
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@thecoreyburton

Thank you for the sample. Will look into it today.

@ChaosKing

Links updated. Thank you.
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Old 16th June 2019, 17:32   #72  |  Link
videoh
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@thecoreyburton

You can improve the contrast on the dog with:

dghdrtosdr(roll=0.8,light=300)

I am looking at ways to mitigate the desaturation of blue in the sky.
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Old 17th June 2019, 15:14   #73  |  Link
videoh
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I've got the blue desaturation issue fixed very simply. I will also revise the roll default. I have to do the Vapoursynth properties and then I will make a release.
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Old 17th June 2019, 15:31   #74  |  Link
thecoreyburton
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Alright, I'll stay tuned. Thank you for going to all that trouble.
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Old 17th June 2019, 16:11   #75  |  Link
videoh
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No trouble at all. Thank you for your valuable feedback.
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Old 17th June 2019, 21:37   #76  |  Link
kolak
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Those are most likely separate grades, so they will never look the same. Saying this grab with HDR to SDR doesn't look good at all.
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Old 18th June 2019, 02:26   #77  |  Link
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For references, here are the results of Reinhard and Mobius from VS Tonemap plugin using the defaults.



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Old 18th June 2019, 02:38   #78  |  Link
videoh
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The blues will come back with the next release. I already have it working. Gotta do the VS props stuff.
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Old 18th June 2019, 13:42   #79  |  Link
kolak
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For references, here are the results of Reinhard and Mobius from VS Tonemap plugin using the defaults.
Those look much better.
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Old 18th June 2019, 22:28   #80  |  Link
videoh
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I released DGHDRtoSDR 1.12 (see first post in thread). Parameters have changed so please read the text file. The default values look much better with thecoreyburton's sample. Feedback will be appreciated on "best" default values. The Vaporsynth properties are now set correctly after the 2020->709 conversion.

Last edited by videoh; 18th June 2019 at 22:33.
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