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Feathered Mask looks bad

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Matt KorshisFeathered Mask looks bad
by on Aug 22, 2011 at 11:44:46 am

Hi Guys,
Not particualy sure how to explain this problem so please bear with me. I am attempting to create a basic animated mask to use as a transition. Effectivley a black solid with an oval mask with animated expansion. So starting on black screen the oval animates outwards revealing the layer underneath. The mask is also feathered quite high.

The problem is when I render the clip and watch it there are these ugly circular 'lines' within the feathered area of the mask as it expands. See picture.

The footage underneath was shot on a 60d. I wondered if the compression in the footage had something to do with it. I have tried lots of different scenarios without working out what the problem is. I hope it is something simple I am missing.


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ben g ungurenRe: Feathered Mask looks bad
by on Aug 22, 2011 at 2:19:22 pm

What you're experiencing is called "banding." Essentially it is caused by mathematical messiness when when you have slight gradients spanning a large area. Here are two ways I have corrected the problem:

1. Add a grain effect to your mask, which scatters the values and effectively hides the banding

2. Change your project from 8-bit to 16- or even 32-bit. Do this by option(or alt) clicking on the "8bpc" at the bottom of your project window. By increasing the bit depth, you are allowing AE to use more decimal places (more or less) causing the math to be more precise, thus reducing the banding errors.

Ben Unguren
Motion Graphics & Editing

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Matt KorshisRe: Feathered Mask looks bad
by on Aug 22, 2011 at 10:18:49 pm

Hi Ben,
Thanks heaps for your reply. I have changed the project to 32bit without any notable change to the banding.

I have had a look at adding grain, could you please let me know typically which functions on the add grain effect you would adjust to smooth out the banding. Sorry I am fairly new to AE and I realise every scenario is different but wondering if you could point me in the right direction.

I really appreciate your time,

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Angie TaylorRe: Feathered Mask looks bad
by on Aug 23, 2011 at 9:18:17 am

If you are only seeing this in your render and not in the preview within AE then it's to do with your output settings. Make sure you render at best quality and that you use a codec that does not compress your footage in this way. The Quicktime animation Codec is a good choice.

hope this helps.



Angie Taylor animation & illustration for television, film, web and devices
Twitter: theangietaylor
Linkedin: theangietaylor

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