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View Full Version : Targa File with Border edges, how to fix

LiChih
06-03-2008, 05:45 AM
Whats up guys~.

I recently started on my first composite work. I rendered our all my files in targa and i Imported my files in After effects. I slapped on a background image behind all my targa and realize there is a tiny thin border line that came with the render. I was wondering is there a way to get rid of it? I was told just to blur out the image a little and I should be good. I was wondering what are you guys doing when approaching this situation?
lunat1k
06-03-2008, 08:34 AM
Did you render against solid black background? What is the fringe like - dark/light?
scrimski
06-03-2008, 09:06 AM
Sounds like an issue with premultiplied alpha.

Change the alpha interpretation in the footage properties.
Rickmeister
06-03-2008, 10:18 AM
Sounds like an issue with premultiplied alpha.

Change the alpha interpretation in the footage properties.

Yeah, that should do the trick.

Premultiplied alpha works pretty good, but leave a half-pixel border behind. When its a bright alpha channel color on a bright background you won't see it, same goes for dark alpha color on a dark background. Changing the alpha properties to the exact color will do a better job of removing that border.
beaker
06-03-2008, 06:25 PM
Premultiplied alpha works pretty good, but leave a half-pixel border behind. When its a bright alpha channel color on a bright background you won't see it, same goes for dark alpha color on a dark background.No, there will not be a boarder at all unless you are doing it wrong. If you are getting a funny boarder you need to either make sure the app knows it is premultiplied, if it doesn't have that option then you need to unpremultiply the image before color correcting it and the repremultiply.

The trouble is some applications don't know how to deal with premultiplied alpha properly and will cause weird boarder issue when you color correct or blur. Compositors like Nuke, Shake, Digital Fusion do not have this problem.
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06-03-2008, 06:25 PM
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