Getting rid of black fringe when using anti-alised alpha channel

JC
Posted By
Jon_Clarkson
Mar 16, 2008
Views
329
Replies
3
Status
Closed
I want to take images rendered in Lightwave 9.3 into Photoshop CS2 for compositing. If:

1. I render objects with antialiased edges over a black background, and then
2. save out the alpha channel for use as a layer mask in Photoshop

I get a black fringe around the objects resulting from the semitransparent pixels of the antialiased edges revealing the black background in the base image.

How should I avoid this problem to get clean antialiased edges?

Thanks.
Related Tags
alpha black channel

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PF
Peter_Figen
Mar 17, 2008
How well does Layer>Matting>Remove Black Fringe work?
H
Ho
Mar 17, 2008
One of the few uses of the Image>Adjust>Brightness/Contrast is choking or spreading Alpha channels. Go to the channels palette and play around with the Alpha to see what happens. Bear in mind that you may want to load the channel as a selection (or not), invert the selection (or not), Modify the selection to expand or contract… (or not), etc, etc.

The point of all the "or nots" is that there is more than one way to attack this. Your willingness to experiment will determine whether you succeed (or not).

<http://img369.imageshack.us/img369/103/alphaon3.jpg>

<a href="http://img369.imageshack.us/my.php?image=alphaon3.jpg" target="_blank"><img src="http://img369.imageshack.us/img369/103/alphaon3.th.jpg"
JR
John_R_Nielsen
Mar 17, 2008
Use the Other > Minimum filter.

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