You all must see what Greg Fraser did in response to my request for
suggestions on how to turn blonde hair into black. It's a superb job,
absolutely first rate. Here's the link, followed by his
description of the process:
http://bit.ly/10PzU8
Hi John. I am not sure what you want to use the photo for but if its just
to see what black hair would look like then this might do the trick.
It was just a matter of creating a new layer in Photoshop, desaturating the
new layer, masking off the hair and then burning the grey hair to make it
black. After that I had to blur a bit where the highlights met the new
darkened hair. Then I decreased the opacity of the new layer to about 85% to
allow some of the light of the original layer through. Then a little touchup
on some wisps of hair and around her hairline