If you have Photoshop, there are two filters which can create normalmaps-- one in the Filterforge database (this program is commercial, though), and a free filter by Nvidia in their "Nvidia Tools" section or something like that.

I think there's a GIMP filter as well, but I've never used it as of yet.

As a general rule, though, when you use a Photoshop or Gimp filter to convert an image to Normalmap, you want to add a Gaussian blur of... what was it, 0.5 to 1.0 or 1.0 to 1.5?  I can't remember.  Anyway, you may want to up the contrast of the image after grayscaling it, then add the blur, before you use the Normalmap filter.

Edit: Sorry, I misunderstood the TC's post.  Though maybe this info will be useful to someone...

Edited by iceempress on 05/29/13 12:16 AM.