Online Seminars from Photoshop Tips & Tricks...
Now, develop the illusion..
Now, show your button face, (again, keeping it on the top layer) and use the same Brightness/Contrast setting. This time, begin backing off so that the shadow areas will begin to lighten. Watch the upper edge of the bevel as you lighten until you arrive at a mid point.
We've labeled the layer "Lighter" edges in the picture above. (We like to label the layers for these demonstrations, but usually don't for the actual job.)