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Old 12th January 2021, 17:42   #1441  |  Link
aron7awol
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Originally Posted by chros View Post
Sky algo: yes, it works like that. But when it does work when it shouldn't, then what's point of ruining the content? That's what I meant about not usable at all.
So what does it do in that scenario, result in a target < DPL?
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Old 12th January 2021, 18:03   #1442  |  Link
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That's correct, resulting in target of DPL. So from the target view it is not an issue, but in reality it modifies the content, e. g. removes fine datails from it even if it's not needed.
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Old 12th January 2021, 18:21   #1443  |  Link
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That's correct, resulting in target of DPL. So from the target view it is not an issue, but in reality it modifies the content, e. g. removes fine datails from it even if it's not needed.
Are you sure it actually modifies the content? I thought it just modified the FALL used for the DTN algo calculation for targeting purposes, but didn't actually modify anything. Is the end result on-screen any different in that scenario?

Now in the dynamic clipping scenario, if it's actually modifying the content before it determines whether that's even necessary, I agree, that's a bug to me.

Last edited by aron7awol; 12th January 2021 at 19:47.
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Old 13th January 2021, 00:00   #1444  |  Link
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Both are the same
Sky algo works based on histogram and yes it modifies the content (same as dynamic clipping) , that's why you have less FALL with it. How much it is visible, good question, depending on its values and content. There was a pj user who stated anything above 5 (strength) is harmful
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Old 13th January 2021, 00:57   #1445  |  Link
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Both are the same
Sky algo works based on histogram and yes it modifies the content (same as dynamic clipping) , that's why you have less FALL with it. How much it is visible, good question, depending on its values and content. There was a pj user who stated anything above 5 (strength) is harmful
Just because the FALL reported on the OSD by madVR is lower (which is the FALL it is using for target calculation) doesn't mean that it actually modified the content. In fact, can you imagine how much of an impact it would have to have on the image in order to actually reduce FALL that much! It would have to dim the sky like crazy. So I'm almost 100% sure that it just ignores the "sky" as part of calculating FALL, which is only used for target calculation. So there's no bug, it has no negative impact if it does that even on a frame with peak < DPL, because the target just ends up as DPL anyway.

So really, if I understand the way it works correctly, it can't modify the image itself, the only effect it can ever have is to potentially change the target (but never below DPL, of course), which is the point of it, anyway. It's an additional intelligence, doing something similar to what the avgHL ceiling is trying to accomplish. I think some thought it would make the ceiling redundant, but I think that both have their place based on my testing.

Which user said a strength of 5 was harmful? I'm interested in reading about their experiences. Are you sure they weren't talking about dynamic clipping?

Edit: Just tested this. It definitely only affects the reported FALL and resulting target. I was able to compare the same frame on two different profiles with the same target and one with a drastically lower reported FALL than the other, but the two images were identical.

Last edited by aron7awol; 13th January 2021 at 01:31.
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Old 13th January 2021, 01:04   #1446  |  Link
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I'm sure, here it is. Doesn't the histogram changes by it?
Can you ask madshi about this just in case?
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Old 13th January 2021, 01:10   #1447  |  Link
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I see no change in the histogram. Reported FALL dropped from 223 down to 151 but image is identical. I'd like to think I could notice that much of a FALL difference.

I don't know if that guy was confusing effects of HSTM with sky or just seeing a target difference or what, but what he reported doesn't make any sense to me based on what I've seen and what I read previously about the sky algo.
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Old 13th January 2021, 01:26   #1448  |  Link
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I'm pretty sure the sky detection is just to avoid dimming scenes that contain a "sky", where it wouldn't improve the resolved highlights in the picture by tonemapping at a higher target.
It's not supposed to change the image.
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Old 13th January 2021, 05:13   #1449  |  Link
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Yeah, and I've been running it on 100 strength for a while now and I've never seen it cause a single issue, possibly because we're pretty much immune to it causing any potential issues because our targets just can't go all that low due to high DPL.

I think it's similar to what the guys in the AVS thread are seeing with grain right now. That's only an issue at low DPLs because the curve can end up rolling through the area where that grain falls, but for us, we're pretty much always 1:1 mapping down in that area.

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Old 13th January 2021, 17:28   #1450  |  Link
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As for dynamic clipping, I agree, we don't want it working when peak < DPL, but I wonder if the logic of having it on always is that if we're toeing the line of DPL, we don't want it turning on and off within the same scene. But of course that situation could be dealt with with some additional intelligence of seeing if we're near DPL, leveraging the scene detection algo to smooth the transition, etc. My guess is madshi just didn't see all that as worth the effort and left it on always, but it would be nice for the user to be able to decide if they want it disabled when peak < DPL instead in the meantime and accept the risk of it potentially pumping on and off in that edge case.

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Old 13th January 2021, 20:04   #1451  |  Link
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So I generated a measurement file as a test to see what it contained. What do you guys use to analyze the resulting measurement files, this?

https://www.avsforum.com/threads/mad...#post-57433788

That tool only seems to give limited info on frames (peak nits, LUMs, and HUEs) and scenes (scene peak), and it shows some percentiles which would be really useful if they were related to frames or scenes but instead they are percentiles of the entire file.

Do you guys know of a way to get more granular data out of the measurement file, or is this all it contains?
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Old 13th January 2021, 22:25   #1452  |  Link
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Before a tool there was an Excel spreadsheet, you can try finding that one.
Probably doesn't have new calculations or something, but you'd have access to the data.
Sadly I don't think Soulnight ever shared the code.

An alternative would be parsing the measurement files, but I don't know the format.
If you find a description of the fields, I might look into it.

I also found the other one: https://www.avsforum.com/threads/mad...#post-57433788
May have more what you're looking for.

Last edited by quietvoid; 13th January 2021 at 22:36.
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Old 13th January 2021, 23:21   #1453  |  Link
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Thanks. Unfortunately, that's the same tool I tried

An Excel spreadsheet sounds good, I'll look for that.
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Old 13th January 2021, 23:40   #1454  |  Link
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I don't know any other tool we can use for measurement files, only this one (let alone the docs for it ).
Basically, these were the "offline" variant of the histogram on the OSD, that's why only the brightness and hue histogram data is in it.
- on the main tab you can double click on:
-- an "avg xxx% frame peak" row (in the middle column) -> yellow graph will appear on graph
-- a scene row )on the left column to get a scene histogram + graph
--- here you can double click on a frame to get both histogram
- right click on a row -> export to txt

Can you upload the measurement file somewhere? (e.g. 7zip-ed to wetransfer.com) Thanks

Edit: I saw quietvoid already replied
@quietvoid: you can export it into txt (see above) if you like

Sky detection: thanks guys, then I remembered wrong, so it's not a bug I don't see any changes in the image here either.
(Btw, I used 700/60 because I switched off sky algo (=0).)
So, what values should we use for this during testing? 100, 20, 20, 20?

About dynamic clipping: I'm certain that is indeed a bug there's no hidden meaning behind it.
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Last edited by chros; 13th January 2021 at 23:42.
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Old 13th January 2021, 23:59   #1455  |  Link
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Quote:
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I don't know any other tool we can use for measurement files, only this one (let alone the docs for it ).
Basically, these were the "offline" variant of the histogram on the OSD, that's why only the brightness and hue histogram data is in it.
Hmm, so if the measurement file doesn't actually contain the frame by frame data that we would need to get the pieces of data I listed in my sheet, then I guess we're stuck compiling most of it manually (and unable to get the rest of the data that I really wanted). Maybe once madshi gets back on the target topic we can get him to dump some additional data on the OSD or in a measurement file.

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Can you upload the measurement file somewhere? (e.g. 7zip-ed to wetransfer.com) Thanks
Sure, but I should probably do The Grinch rather than the random short episode I did just as a test

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Sky detection: thanks guys, then I remembered wrong, so it's not a bug I don't see any changes in the image here either.
(Btw, I used 700/60 because I switched off sky algo (=0).)
So, what values should we use for this during testing? 100, 20, 20, 20?
Maybe the 100 10 20 20 that Neo-XP uses? I know he's done extensive testing with it, and if that's not harmful for his lower nits I'm certain it won't be for us!

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About dynamic clipping: I'm certain that is indeed a bug there's no hidden meaning behind it.
Bug or not, the edge case I considered would be a real problem, but that's not to say we shouldn't be able to disable it when peak < DPL! After all, it's just an edge case. I'm just giving madshi the benefit of the doubt.

Last edited by aron7awol; 14th January 2021 at 00:04.
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Old 14th January 2021, 00:09   #1456  |  Link
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Hmm I would think there is frame by frame data, it was just grouped by scene to verify scene cuts.
Otherwise there's no way you can do such a graph scene by scene..
For example: https://www.avsforum.com/attachments...3-jpg.2512358/

Anyways, here's the post detailing the format: https://www.avsforum.com/threads/imp...#post-57030812
I don't have a measurement file laying around anymore..

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Old 14th January 2021, 00:34   #1457  |  Link
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Quote:
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Hmm I would think there is frame by frame data, it was just grouped by scene to verify scene cuts.
Otherwise there's no way you can do such a graph scene by scene..
For example: https://www.avsforum.com/attachments...3-jpg.2512358/
Yes, and when you double click on a row on the table you will get the histogram data graphs.
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Old 14th January 2021, 01:28   #1458  |  Link
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So I decided to test Dynamic Clipping a bit, because I've never actually turned it on, and I wondered if it could be useful to us. After all, a lot of us like the sometimes pretty heavy clipping that using higher DPLs than our actual panel peak nits gives us, so I wanted to see if Dynamic Clipping 100 would be similar, stronger, or weaker than that.

I used the scene at the beginning of Valerian that I've seen others in the AVS thread use to show what Dynamic Clipping does. And I actually think, based on the testing I just did, that similar to the Sky Detection, even though the OSD always shows a change, it doesn't actually kick in when peak < DPL.

At first I was just testing at my normal high DPL, and I was thrown off because even though the frame peak was changing in the OSD, suggesting clipping was occurring, I couldn't find any change in the image whatsoever. And so after messing around with other frames and still not seeing any change, I tried a lower DPL, and sure enough, the clipping (in this case, on her necklace) was immediately in my face obvious. So then I started creeping up on DPL, and the clipping became less and less, and once I got up to the original frame peak, there was no clipping at all.

So it seems it actually works exactly as we want it to, where it only clips as much as needed to bring the frame peak down to DPL, but no more, and so if peak < DPL, not at all.
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Old 14th January 2021, 16:38   #1459  |  Link
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Sorry for being a little off topic - does anyone else's LG OLED map the color gamut to wide in PC mode? Even though the option is disabled, after going back and forwards with testing, it certainly seems that mine is mapping to wide in PC mode.

If it makes any difference, full chain in RGB, and both 60 and 23.976 fps (10bit) tested.
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Old 14th January 2021, 18:03   #1460  |  Link
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I also use these modes on my B8, but the gamut option is (!) available in ISF Dark/Bright SDR modes, so I set it to Wide.

Quote:
Originally Posted by aron7awol View Post
I used the scene at the beginning of Valerian that I've seen others in the AVS thread use to show what Dynamic Clipping does. And I actually think, based on the testing I just did, that similar to the Sky Detection, even though the OSD always shows a change, it doesn't actually kick in when peak < DPL.

At first I was just testing at my normal high DPL, and I was thrown off because even though the frame peak was changing in the OSD, suggesting clipping was occurring, I couldn't find any change in the image whatsoever. And so after messing around with other frames and still not seeing any change, I tried a lower DPL, and sure enough, the clipping (in this case, on her necklace) was immediately in my face obvious. So then I started creeping up on DPL, and the clipping became less and less, and once I got up to the original frame peak, there was no clipping at all.

So it seems it actually works exactly as we want it to, where it only clips as much as needed to bring the frame peak down to DPL, but no more, and so if peak < DPL, not at all.
Indeed!!! Thanks for this test!
I just tested the MMFR sample (keyframe at 00:19 sec, frame peak 6344 without clipping), lum max to see the blue patches.
I tried various DPLs 800/2000/4000 and set the clipping according to them: e.g. at 4000 DPL, 40 DC results in 3954 nits. If I use higher DC e.g. 100 no difference in the patches, if I go lower e.g. 39 there is difference (slight) straight away.
So this one isn't a bug either

Does this mean that there's a lower limit at DPL for this?
If so, then why on earth madvr allows the measured nits value to go lower than DPL?! What's the point?
I mean, with DC we clearly have the lower limit which is DPL!!! (Unlike with the sky algo where we don't have a specific lower limit, at least not that straightforward.)
What am I missing here?

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(Btw, I used 700/60 because I switched off sky algo (=0).)
This one kept me thinking: are you sure that the sky algo is useful for us? (try it with The Meg (TM) sample)
Let's take these two profiles (DPL/DTN/SS):
- p1: 800/60/0
- p2: 800/85/100

The purpose of sky detection is the lower the FALL of high FALL scenes so DTN doesn't result in such high ADPLs, allowing to use higher ADPL value (85 vs 60), right?

But this one actually has a side effect:
- high FALL scenes:
-- with p1: they still have high FALL, so we don't need to use high DPL for these
-- with p2: they have way lower FALL, so to compensate we need high DPL
- lower FALL scenes (not really low ones)
-- with p1: we don't have such high ADPLs due to low DTN
-- with p2: we will have higher ADPLs (than peobably is necessary) due to the higher DPL!!!

What do you think?

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Originally Posted by aron7awol View Post
Maybe the 100 10 20 20 that Neo-XP uses? I know he's done extensive testing with it, and if that's not harmful for his lower nits I'm certain it won't be for us!
I agree (if we decide it's useful for us) but that means he changed it in the last 2 months
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