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.

How well does Layer>Matting>Remove Black Fringe work?

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"

Use the Other > Minimum filter.