Did the original image actually have a black background? If so, what tool did you use to separate it? I've used Photoshop and I'm pretty sure the fringing still happens.
@HelloWorld Yes, I really used the image from the previous slide (pink ball on black background). There are many ways you can composite in Photoshop (depending on how you combine and manipulate layers). Some compositing operations will give you fringing; others will not. Based on our discussion of premultiplied alpha, can you come up with a way to do "fringe-free" compositing in Photoshop?