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Old 25th June 2022, 20:06   #241  |  Link
kolak
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Regardless how "strange" MaxCLL and MaxFALL are there is this as an alternative measure (taking into account overshoots problem:

https://postimg.cc/YvJVJCfW
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Old 25th June 2022, 20:42   #242  |  Link
kolak
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Top and bottom bars (as separate files) give similar MaxCLL (just bit above 1000nits).
In the same time max Y is 475 vs 705, so very different and not really appropriate for MaxCLL calculation.



Grab is form QTX, so tone mapped to 500 nits Mac screen (irrelevant here).
Top row is just blue channel of the bottom bars.

This makes those metadata values defined in very confusing way, but I assume there is some idea behind them.
I've just learnt they are very different things than what I thought (even if I remembered them been defined in some specific way).

In the same time in Resolve scopes both peak at around 1000nits, so show up correctly. This means when I grade in Resolve (by scopes to 1000nits) MaxCLL should be 1000nits not more.
So I'm confused by numbers from those titles from the other thread. They should not be so "strange" and random. Very possible most of them have simply wrong values as metadata. Some do look fine though.

Last edited by kolak; 25th June 2022 at 21:04.
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Old 26th June 2022, 06:35   #243  |  Link
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Quote:
Originally Posted by kolak View Post
Regardless how "strange" MaxCLL and MaxFALL are there is this as an alternative measure (taking into account overshoots problem:

https://postimg.cc/YvJVJCfW
Well hello there...
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Old 26th June 2022, 16:15   #244  |  Link
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The whole article (image based): https://0x0.st/oSpl.pdf
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Old 26th June 2022, 21:10   #245  |  Link
kolak
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Hmm...looks like original recommendation wasn't really well thought out. I'm still not very convinced with current formula either.
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Old 26th June 2022, 22:52   #246  |  Link
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Quote:
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Hmm...looks like original recommendation wasn't really well thought out. I'm still not very convinced with current formula either.
It's a bit late to be having this conversation, isn't it?
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Old 26th June 2022, 23:18   #247  |  Link
kolak
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Why too late?
You can always change a formula
MaxCLL may stay as is, but I can see that companies started counting "titles' max brightness" in own ways- more intuitive/representative.
Also for your needs MaxCLL may be simply not the best measure.

Last edited by kolak; 26th June 2022 at 23:21.
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Old 26th June 2022, 23:30   #248  |  Link
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If MaxCLL is retroactively reinterpreted to mean Y instead of maxRGB, television sets are going to suck at tome mapping.
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Old 27th June 2022, 09:48   #249  |  Link
kolak
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They unlikely to change this, but you can ( if old way is not really representative).
Do TVs actually use it? Apparently many TVs don’t.
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Old 27th June 2022, 16:12   #250  |  Link
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Quote:
Originally Posted by kolak View Post
They unlikely to change this, but you can ( if old way is not really representative).
Do TVs actually use it? Apparently many TVs donít.
MaxCLL tells you how aggressively you need to tone map.
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Old 27th June 2022, 20:03   #251  |  Link
kolak
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Unless TVs does it dynamically in realtime ?
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Old 27th June 2022, 20:50   #252  |  Link
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Unless TVs does it dynamically in realtime ?
@FranceBB: Do TVs really do this?
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Old 27th June 2022, 23:53   #253  |  Link
FranceBB
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Yes, but only some brands and it really depends.
The idea was to cope with missing mandatory info.
Although those values are mandatory for PQ streams, a relatively high number of files spreading all over internet didn't have those and Samsung saw that coming.
To put this into context: I gave to the TV a PQ without metadata other than the fact that it was PQ BT2100 and the TV worked that one out surprisingly well.
When it comes to metadata actually being there, though, it's a different story and I found out that some manufacturers respect them and some other don't and do their thing anyway.
Again this is due to the fact that some of them are just wrong.
On the other hand, I did make a test by giving Samsung a PQ file that was artificially stretched to occupy all the available values from top to bottom and then I told the TV that it was 1000 nits (it wasn't). The result wasn't completely wrong in the sense that the TV did adjust something and recognised that something was wrong, but it still did a fairly poor job cause while some scenes were looking good, some others almost made me blind, especially when red was involved.
Still I'm pretty sure that some TVs do something to correct the result, but can still get it pretty wrong if the value is wrong.

And of course you'll never have any of those issues with HLG, which is also an added benefit of using it.

Last edited by FranceBB; 27th June 2022 at 23:55.
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