Oh! It is a filter?
(
LordManley twitter.com/LordManley,
Fri 22 Feb 2008, 20:06,
archived)
Yep, dead easy.
But first grayscale the image, then go to...
actually curves are quite complicated. I shall give it a bash soon.
(
Captain Wow currently being a cunt in Infamous,
Fri 22 Feb 2008, 20:07,
archived)