TechDude's got the technical details nailed down. As for me, I've taken a different approach -- one of trying to recreate the text on the Kos image.
What I've learned is that there is one, and only one, way to make an image look like the Kos image, and I'm pretty sure that it was done to the original scan before it ever made its way into Photoshop.
68 posted on 07/15/2008 8:13:58 AM PDT by Polarik
(obama, birth certificate)