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Banding in After Effects
Hi,
Don’t know if I should be posting this in After Effects forum or Avid. I’m editing a project that is for use on HD screens as the primary destination, but will eventually get transferred to film for theater use. I didn’t shoot the footage and was only brought in to edit/graphics. The talent was shot on black backgrounds but depending on the lighting, I get different degrees of spill. In some shots the background is very dark, and in others it shows up more. The footage was shot on Panasonic Varicam at 720p/60 and was brought into Avid Symphony as is. The bin shows DVCPro HD (720p/60) for all footage. I’m exporting the footage out using the native codec and keeping everything set to match how the footage was shot. Then in After Effects I’m compositing the elements with background images/footage and using mattes with heavy feathering so that all edges are nice and soft. It looks fine in After Effects. In most cases I’m using a matte around the main part of the ima ge (the on cam talent) and then placing a black solid under them. I render the comps still using the DNxHD settings to match the footage and Avid sequence settings, which were set based on the footage specs. Again, transferring to film is a secondary priority that may or may not happen, so we set up the sequences for the primary delivery needs.
I’ve read some of the other posts about this and have tried a few things based on what others have done. But I’m still getting the banding and artifacts. So I apologize if this post is something that has already been addressed, but I need some advice based on my specific situation and I know there are many of you who have already been down this road and might be able to help.
I’ve tried the Tinderbox Deband filter and that didn’t work on the first attempt. Perhaps there’s more to using that plugin outside of just applying it and tweaking the settings to get the right look. I’ve also tried changing the project settings in AE to 16 bit, with and without the checkbox for Blend Colors Using 1.0 Gamma. I tested them side by side after importing the renders back into Avid, and I see some difference, but still have more banding than the producer would like to see.
Is there some other way to export the footage from the Avid so that I get a higher quality? I know, that’s an Avid question. My feeling is that I should keep the footage in the native spec.
Or is there more I can do in AE? I have a few days left to fix this, so I’m ok at the moment, and if I can’t fix it it’s not the end of the world. I would just like to deliver the best image possible.
Thanks so much for the help!
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4 Replies
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There’s a lot in your post, so I apologize if I misread or misunderstood.
Here are a couple of things to think about with regard to banding:
– Make sure that you’re not checking image quality on a cheap (i.e., common) LCD monitor. Many LCDs are effectively 6 bits per channel; so, it doesn’t matter if you’ve got smooth 16-bpc gradients in the data if the image is being quantized to much less precision on your preview device. (You didn’t actually say what device you were seeing the banding with.)
– After Effects introduces dithering to reduce banding any time the data passes through an 8bpc bottleneck. E.g., if you’re outputting to an 8bpc format, After Effects will dither the colors in the rendering phase. You can use this factoid to force dithering earlier by applying an adjustment layer that does nothing but uses an 8bpc effect—such as the Arithmetic effect with the default settings.
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Todd Kopriva, Adobe Systems Incorporated
putting the ‘T’ back in ‘RTFM’ : After Effects Help on the Web
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Blurring just the Red CHannel (Channel Blur plugin) does wonders.
Cheers
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These look like FAQ answers to me!
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Ok I got most of the banding reduced by about 80-90 percent, so now it is at an acceptable point at least. Thank for the posts. I got some good advice from a great guy at Film Workers in Chicago that along with knowing I would need to add noise to the AE comps worked fine. I used an adjustment layer on each comp, and applied noise at either 3, 4 or 5, depending on the shot, and unchecked color noise. Then re-rendered everything, it look MUCH better although not perfect. Next time I will insist on having a little more say on how it’s shot. Turns out it was shot on Panasonic 2000 and captured on P2 cards, so it was 8 bit from the beginning. Then the Avid (8 bit), which made me leave the project settings in AE at 8 bit. I then rendered using Animation to avoid any further compression and this made a hugh difference.
Thanks again for the responses! I’ll be back I’m sure.
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