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Crazy blue shimmer with Lumetri Black level

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mark thompson
Crazy blue shimmer with Lumetri Black level
on May 13, 2018 at 10:58:18 am

I've had a problem for a while that I've only just managed to nail down. When a relative noisy part of the image where Lumetri is being asked to darken the blacks contains dark blues or any dark color, the blues come alive.
Rather than darkening that part of the picture it gets an almost dayglo blue.
Each frame is different and so when the clip is played it shimmers and really draws attention to a part of the picture that you are intending to hide ☹

I had been blaming the camera in the past or even the Keying software. However it seems to be the Lumetri panel in CC 2018 (although it has been there for a few years in earlier releases).

Anyone seen this before or have a plan for dealing with it?







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Dave LaRonde
Re: Crazy blue shimmer with Lumetri Black level
on May 13, 2018 at 5:01:46 pm

It's a mistake made when shooting.

Those windows in the background are really blown out! There is NO INFORMATION about the image in those areas.

So how do you fix it? You re-shoot, putting neutral density filters on the outsides of those windows. If you can't re-shoot, you, sir, are stuck with what you have and you can only make the best of it.

I'm just a producer and I know this neutral density trick. I am STUNNED you didn't realize the implications of the shot as you were setting up. Remind me not to hire you.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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mark thompson
Re: Crazy blue shimmer with Lumetri Black level
on May 13, 2018 at 7:27:03 pm

Dave,
the point of the shot was just to show people arriving, there's no real interest in what is beyond the windows. That room is fourteen floors up so no chance of nd sheets on the outside. Also the point of the room is to showcase the city below [to people that go to the edge and look]. Sp there are windows all around. I've plenty of shots that aren't blown out.

The only reason I posted that shot here is that it showed the blue shimmer on the suit.

I will be shooting there again. Next time even the B roll will will be framed more carefully.


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Kalleheikki Kannisto
Re: Crazy blue shimmer with Lumetri Black level
on May 13, 2018 at 5:28:45 pm

Although not related to Lumetri (I don't use it that much for color correction), shadow areas have that issue on some of my projects as well. What I usually do is one (or more) of the following:

- tone down color correction, especially at the shadow end
- use selective color to tone it down (reduce the blue balance in blacks and blues)
- desaturate the shadow end

In your case, you might want to do those steps before the Lumetri correction on the chain.

Kalleheikki Kannisto
Senior Graphic Designer


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mark thompson
Re: Crazy blue shimmer with Lumetri Black level
on May 13, 2018 at 7:31:28 pm

thanks, I will give those a try.


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greg janza
Re: Crazy blue shimmer with Lumetri Black level
on May 13, 2018 at 9:46:32 pm

That image looks highly compressed. What camera are you shooting with? What format?

Your blacks are highly crushed and you have all kinds of mixed lighting in this shot. To me this appears to have more to do with the camera settings, how you're setting up your framing in the field and your level of compression in the recording codec.

Windows 10 Pro | i7-5820k CPU | NvidiaGeForceGTX970 | Blackmagic Decklink 4k Mini Monitor |
Adobe CC 2018 |Renders/cache: Samsung SSD 950 Pro x2 in Raid 0 | Media: Samsung SSD 960 PRO PCIe NVMe M.2 2280 | Media: OWC Thunderbay 4 x 2 Raid 0 mirrored with FreeFileSync


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mark thompson
Re: Crazy blue shimmer with Lumetri Black level
on May 14, 2018 at 12:02:17 am

the cam is a sony pmw200. mpeg2 50M 422.

The ciip above was rendered to match the source.

The reason it looks compressed here is YouTube compression, it is much less compressed on the original.

mark


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greg janza
Re: Crazy blue shimmer with Lumetri Black level
on May 14, 2018 at 1:19:36 am

It’ll be a lot easier to assess your footage if you can post up a camera original clip that can be downloaded.

Windows 10 Pro | i7-5820k CPU | NvidiaGeForceGTX970 | Blackmagic Decklink 4k Mini Monitor |
Adobe CC 2018 |Renders/cache: Samsung SSD 950 Pro x2 in Raid 0 | Media: Samsung SSD 960 PRO PCIe NVMe M.2 2280 | Media: OWC Thunderbay 4 x 2 Raid 0 mirrored with FreeFileSync


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Oliver Peters
Re: Crazy blue shimmer with Lumetri Black level
on May 14, 2018 at 11:24:44 pm

It's not just the suit. The African-American man's face is doing the same thing. Your color correction has crushed the shadow information too much. How does this shot look on the Lumetri scopes? I'd bet these areas of the image are at 0 - or crushed well below 0. If so, try bring this up so the darkest parts of the suit and face are in the 10-20 IRE range and see if you get better results.

Oliver

Oliver Peters - oliverpeters.com


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mark thompson
Re: Crazy blue shimmer with Lumetri Black level
on May 15, 2018 at 6:45:27 am

the background to this shot is that it is a little underexposed when I filmed it. However at that point I was on auto so it is what the camera thinks it should be. On my first render I had just hit the "auto" button and then all shimmer started. Lumetri suggested raising the exposure a little and darkening the blacks. I played around with the two settings, set the exposure back to zero - that made no difference. In the version I posted I adjusted the blacks to -7. When I remove Lumetri from the chain - it looks a lot better.

Perhaps it is just expectation but when I set the black level to -7 I hoped it would just darken the darker parts of the picture. It is probably true that I am trying to darken parts of the picture that don't need darkening. However I still don't understand how it gets all that shimmer.


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Oliver Peters
Re: Crazy blue shimmer with Lumetri Black level
on May 15, 2018 at 12:51:05 pm

[mark thompson] "On my first render I had just hit the "auto" button and then all shimmer started"

Auto is almost never a good thing.

[mark thompson] "but when I set the black level to -7 I hoped it would just darken the darker parts of the picture"

Yikes. Do you mean 7 BELOW 0 on the scopes? You are crushing the video, which is causing posterization (your "shimmer").

Not offense intended, but I think a color correction tutorial - especially one focused on Lumetri - might be helpful.

- Oliver

(PS: Sorry if this post is a duplicate. My first reply never showed up.)

Oliver Peters - oliverpeters.com


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mark thompson
Re: Crazy blue shimmer with Lumetri Black level
on May 15, 2018 at 1:47:51 pm

>> Yikes. Do you mean 7 BELOW 0 on the scopes?

On the Lumetri Tone panel, 0 is the level you recorded at. Then you can go + or - 99.
On the scopes panel, it goes from 0 to 100 [float for me]. So I don't think you can take it below 0 but you can go above 100.

It is interesting as to what the blacks do. On Adobe help they referenced someones blog entry. It does not add a lot of clarity:

http://rneilphotog.com/2017/06/lumetri-basic-tab-what-do-the-tonal-controls...


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greg janza
Re: Crazy blue shimmer with Lumetri Black level
on May 15, 2018 at 2:57:41 pm

After doing a baseline color grade, if you still feel that individual areas of your frame need adjusting, the secondary color grade within the lumetri panel can be very helpful:







Windows 10 Pro | i7-5820k CPU | NvidiaGeForceGTX970 | Blackmagic Decklink 4k Mini Monitor |
Adobe CC 2018 |Renders/cache: Samsung SSD 950 Pro x2 in Raid 0 | Media: Samsung SSD 960 PRO PCIe NVMe M.2 2280 | Media: OWC Thunderbay 4 x 2 Raid 0 mirrored with FreeFileSync


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mark thompson
Re: Crazy blue shimmer with Lumetri Black level
on May 17, 2018 at 11:01:01 pm

I like the video, I have used that before but not very much.
I turned the blue jackets green!
Alas it was a noisy green. I'm still testing though.


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Oliver Peters
Re: Crazy blue shimmer with Lumetri Black level
on May 15, 2018 at 5:02:54 pm

[mark thompson] "It is interesting as to what the blacks do."

Look at the last graphic at the bottom of that blog post. That's what is happening to your image. Not as extreme, but in general. Because you also have chroma, it has additional effect to the chroma, which is what you are interpreting as "shimmering".

- Oliver

Oliver Peters - oliverpeters.com


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Rich Rubasch
Re: Crazy blue shimmer with Lumetri Black level
on May 17, 2018 at 3:29:04 pm

Hey all....this is not a factor of his footage....we've seen this bug in lumetri since CC2017 came out. We actually have copied the CC2015 version of Lumetri into our CC 2017 install to solve this bug.

I noticed it one day on a headrest in a car interior....had never seen it before. Once you see it you'll know what it is, and it's Lumetri. We finally solved it by purchasing Colorista and installing that in all our systems.

Four editors here all confirmed this bug that found its way into Lumetri in CC 2017.

If you can, try this same effect on the same clip in CC 2015 Premier and you will see smooth blacks and no increase of saturation in the blacks.

What's worse, if we color correct on one system and then open the same project in another system and make any adjustments to any setting in Lumetri, the entire clip changes it's overall look completely. As if Lumetri could not replicate what it had done on the other system....all our systems are the same....and we tried it with software only turning off any video card processing.

It's Lumetri in CC 2017 and CC 2018. CC 2015 was rock solid across all our systems.

Rich Rubasch
Tilt Media Inc.
Video Production, Post, Studio Sound Stage
Founder/President/Editor/Designer/Animator
http://www.tiltmedia.com


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mark thompson
Re: Crazy blue shimmer with Lumetri Black level
on May 17, 2018 at 11:07:09 pm

thanks for that post, I'm glad I'm not the only one! I will try Colorista and see how that works.

I've also got Neat so I'll be busy for a few days.

mark


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Rich Rubasch
Re: Crazy blue shimmer with Lumetri Black level
on May 18, 2018 at 2:19:41 pm

But the easiest test is to open the same clip in any CC 2015 version and see how Lumetri performs there. If it works then you can copy the Lumetri plug in to the CC 2017 or 2018 build and use it there without issue.

Rich Rubasch
Tilt Media Inc.
Video Production, Post, Studio Sound Stage
Founder/President/Editor/Designer/Animator
http://www.tiltmedia.com


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greg janza
Re: Crazy blue shimmer with Lumetri Black level
on May 19, 2018 at 5:40:39 pm

I wish I still had Adobe CC 2015 to experiment.

I haven't noticed this issue at all on my system or on any of the other edit systems that I've worked on.

Is it possible that it's actually more of a GPU related issue and not a Premiere bug?

Windows 10 Pro | i7-5820k CPU | NvidiaGeForceGTX970 | Blackmagic Decklink 4k Mini Monitor |
Adobe CC 2018 |Renders/cache: Samsung SSD 950 Pro x2 in Raid 0 | Media: Samsung SSD 960 PRO PCIe NVMe M.2 2280 | Media: OWC Thunderbay 4 x 2 Raid 0 mirrored with FreeFileSync


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