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Crazy blue shimmer with Lumetri Black level
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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17 Replies
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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 endIn your case, you might want to do those steps before the Lumetri correction on the chain.
Kalleheikki Kannisto
Senior Graphic Designer -
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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thanks, I will give those a try.
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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 -
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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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 -
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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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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[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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>> 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:
https://rneilphotog.com/2017/06/lumetri-basic-tab-what-do-the-tonal-controls-really-do/
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