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Removing posterization
Hi
does anyone have a workflow for dealing with posterization? In particular I have some sky shots of clouds (dark grey stormy ones) taken on a canon 7d. As soon as I change contrast or add color correction, the image becomes posterized. I have tried adding noise and later removing with neat video, but this is very time consuming.I have converted the clips into prores 422 hq.
Declan Smith
https://www.madpanic.tv
FCS3 / After Effects CS4 / Combustion / Canon 7D / Canon XL2 -
6 Replies
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How are you doing the grade, contrast adjustments? How are you monitoring the result and are you watching the scopes to see if you are clipping or going to illegal levels.
Also read the recent post about ProRes HQ and try that shot as ProRes only. Perhaps you are seeing why HQ is not recommended for 8bit 1920 x 1080 source footage.
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Hi
I have just read the article on prores, but I don\’t think this is affecting the issue I am facing as I do see the same issue with standard prores. To answer the other points, I am using simple brightness / contrast to make adjustments (to make clouds look more stormy), and monitoring via fcp canvas window. Even when rendered out and played full screen the same issue is present. Also I have used the scopes within fcp to monitor levels and the histogram goes from smooth transitions to being choppy as I increase the contrast.Declan Smith
https://www.madpanic.tv
FCS3 / After Effects CS4 / Combustion / Canon 7D / Canon XL2 -
You should be using the 3-way color corrector.
David Roth Weiss
Director/Editor/Colorist
David Weiss Productions, Inc.
Los AngelesPOST-PRODUCTION WITHOUT THE USUAL INSANITY ™
EPK Colorist – UP IN THE AIR – nominated for six academy awards
A forum host of Creative COW’s Apple Final Cut Pro, Business & Marketing, Indie Film & Documentary, and Film History & Appreciations forums.
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You will get much better control using Color, but 3 Way CC is also quite powerful in FCP, particularly if you get a handle on limit effect controls.
You may also get a good cloud effect with careful use of gradient filters to darken the top of frame. Also check your render settings to make sure you render everything in 10 bit best quality. It might be that you are rendering in 8 bit which won’t help.
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Thanks David & Michael for your comments. I will try some of the other tools and see if that makes a difference, given the source material. I also have the same issue in after effects with the same kind of footage (i.e. 7D H.264 -> prores converted, with graduated areas). Is there any pre-processing / conversion process that can be applied to minimise this effect?
It’s a really nasty type of artifact as I never really know when it’s going to turn up (mostly shot dependent) and sometimes it doesn’t appear until the final encode (either back to h.264 or other delivery codec).
Declan Smith
https://www.madpanic.tv
FCS3 / After Effects CS4 / Combustion / Canon 7D / Canon XL2 -
Maybe this may help, released yesterday:
https://www.phyxware.com/NI_Cleaner_01.html
It claims to fix gradiant banding.
Declan Smith
https://www.madpanic.tv
FCS3 / After Effects CS4 / Combustion / Canon 7D / Canon XL2
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