Alpha Banding

[Paul Rozon]

PP allows you to go from 8 bit to 11 bit in the Matrox sequence settings. Does not make a difference.

I also experimented with 8, 16 and 32 bit in AE and no difference.

I appreciate the suggestions.

[Erik Waluska]

Could you post a CS5 version of your project file?

[Paul Rozon]

Not at my workstation right now but I will upload a cs5 version as soon as I can. Thanks for your interest.

[John Cuevas]

Couple of things. First when I tried to render out an HD file to a AVI with RGB + Alpha, it was unavailable in both HD or SD sizes. If I chose avi with the codec set to none, I was able to render to a RGB+Alpha. Of course umcompressed AVI’s are very very large files, but you can always take that file into Media Encoder.

I posted last week on video banding:

Bit depth can a difference on banding

If the video is for HD delivery, Kevin Camp’s offered a recipe that has worked well for me in the past.

as for banding, you can usually add an adjustment layer with the noise effect on it. it shouldn’t take much noise (less that 5%) to hide the banding.

Roland Kahlenberg offers some notes if for web delivery.

Blurring one or more of the color channels does a better job for reducing or eliminating banding problems. Adding noise more to a comp which may be destined for Web delivery will only result in a poorer quality web version as compressors usually have a harder time compressing noise.

Use Effect>Channel Blur and increase one of the values to solve your problem. You can tell which channel needs more attention by looking at the individual color channels in the Comp Panel prior to applying Channel Blur.

Johnny Cuevas, Editor
Thinkck.com

“I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work.”
—THOMAS EDISON on inventing the light bulb.

[Tudor “ted” jelescu]

I would do the compositing all in AE @ 32bit and render uncompressed. I would then use Encoder to compress the final. This usually eliminates any banding issues.

Tudor “Ted” Jelescu
Senior VFX Artist

[Paul Rozon]

I have experimented with everything at its highest bit rate without success.

What I find confusing is why the alpha keys perfectly on my PP timeline in realtime. That would suggest to me that the alpha is good and that something is going wrong in the render. Is this logic flawed?

[Paul Rozon]

The same suggestion was made in PP forum.

Certainly an option that I will explore but I am confused as to why the alpha looks perfect on PP timeline in realtime and it only craps out on the render?

[Tudor “ted” jelescu]

Most likely you loose info in compression. Try to render an uncompressed format from PPro and see if you have the same results.

Tudor “Ted” Jelescu
Senior VFX Artist

[Paul Rozon]

Just rendered it out as Microsoft AVI, codec set to NONE. Banding still there.

I can see where the render might add some subtle compression banding but what I am experiencing is well beyond that as you can see from the JPG’s that I have attached.

It is a 90min program with many instances of this effect. Bringing everything into AE just to get a clean render and then back into PP is going to kill me for time. Then once the alterations come in it is going to get rediculous.

Is this what the norm is for AE alpha? Or am I dealing with a unique problem?

[Tudor “ted” jelescu]

I have never encountered this issue with alpha from AE in PPro, but then I do all the complex compositing in AE and use only simple gfx with alpha in PPro.

Tudor “Ted” Jelescu
Senior VFX Artist