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Color banding occurs on clip with noise removal and color correction?

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Jake Huddleston
Color banding occurs on clip with noise removal and color correction?
on Dec 14, 2011 at 6:31:43 am

Hi there. I am working on a project in Premiere Pro CS5.5 with the occasional clip dynamically linked to After Effects for noise removal. There is one clip in particular that is giving me trouble when I try to color correct and remove noise from it. My workflow begins in Premiere. I started out color correcting first in Premiere, but then I realized that not all of the color correction effects will transfer to After Effects via dynamic link, so I just saved those color corrections as a preset and applied it after the clip was converted to a linked comp. In After Effects, I used the Neat Video plugin to remove noise from the background of my clip. Since dynamic link is now two-way, the noise was immediately removed from my footage in Premiere. I then applied the color correction preset I saved earlier.

It was then that I noticed that as soon as I added my color correction preset to clip with the noise removed, I was getting severe color banding on the background of my footage, particularly the out of focus areas. There is still a little banding when I add color correction but do not remove noise, but not nearly the same as if I remove noise as well as add color correction. Instinctively it seems to me that somehow color correcting causes some sort of interference with with the noise removing plugin.

A frame of the clip during each step of the process is shown below:
- Image 1: The original image, no color correction or noise removal added.
- Image 2: The image with noise removed in After Effects.
- Image 3: The image, noise removed in After Effects, and a color correction preset added in Premiere.





As you can see, as soon as the color correction preset is added in Premiere, severe color banding appears, most noticeably in the background. I don't know if the problem is an interference between the noise removal plugin and color correction, an incompatibility between AE and PP effects, one of the individual effects that make up the color correction preset, or some other factor entirely. If anyone has any advice on preventing this banding, it would be very much appreciated.

Jake Huddleston


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Angelo Lorenzo
Re: Color banding occurs on clip with noise removal and color correction?
on Dec 14, 2011 at 6:58:08 am

Try upping your color bit precision to 32 bits in After Effects.


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Jake Huddleston
Re: Color banding occurs on clip with noise removal and color correction?
on Dec 14, 2011 at 9:13:21 am

Thank you for the tip, Angelo. I had not done this. However, this has not made a difference in the preview in Premiere Pro. I also checkmarked the maximum bit depth option in the sequence settings in Premiere Pro, with no change. Even exporting with maximum bit depth checkmarked, the banding remained. The problem would have to be the color correction or color bit depth settings in Premiere, wouldn't it? Because the preview in Premiere has almost no banding at all until color corrections are applied, and this is after removing noise in After Effects...

Jake Huddleston


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Jeremy Garchow
Re: Color banding occurs on clip with noise removal and color correction?
on Dec 14, 2011 at 2:17:23 pm

What's your source footage?


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Jake Huddleston
Re: Color banding occurs on clip with noise removal and color correction?
on Dec 14, 2011 at 5:00:29 pm

Source footage are H.264 files from a Canon T2i.

Jake Huddleston


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Jeremy Garchow
Re: Color banding occurs on clip with noise removal and color correction?
on Dec 14, 2011 at 5:31:03 pm

[Jake Huddleston] "Source footage are H.264 files from a Canon T2i."

Then banding is due to the highly compressed 8bit camera footage.

Try adding noise or dither. I know it seems crazy, but it can reduce banding.

Jeremy


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Jake Huddleston
Re: Color banding occurs on clip with noise removal and color correction?
on Dec 14, 2011 at 7:36:04 pm

Thanks! Adding a little grain in After Effects helped a lot. I added the Noise effect, and set the amount of noise to 3.0%. However, I also decided to just do my color correcting in After Effects instead of doing it back in Premiere, which also helped a lot. I am also going to do more research on reducing artifacts and noise in my footage during shooting, so as to reduce the problem in post.

Jake Huddleston


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Jeremy Garchow
Re: Color banding occurs on clip with noise removal and color correction?
on Dec 14, 2011 at 7:47:11 pm

[Jake Huddleston] " However, I also decided to just do my color correcting in After Effects instead of doing it back in Premiere, which also helped a lot. I am also going to do more research on reducing artifacts and noise in my footage during shooting, so as to reduce the problem in post."

There are steps you can take to reduce this, but DSLR footage is extremely compressed. It's just the nature of the beast.

You can run the footage through 5DtoRGB which decompresses the footage differently and attempts to rebuild some of the lost color info. I would leave it up to you to see if you notice a difference.

http://rarevision.com/5dtorgb/

The shot that you posted would be a good tester shot due to the soft background.

Jeremy


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