sau0305,
the white edge you saw could well be the artifact resulted from the mindless Photoshop sharpening I did. But could be other reason, I will see if I can find out more and report later.
By the way, for those who are interested in IR, here is a good link to explore:
http://forums.dpreview.com/forums/read.asp?forum=1009&message=7103089
gappy shppoting