Warhol Effect?

[jjhunter]

Hey all--

I'm playing around with some banner designs for a comm I run, and someone suggested doing a Warhol-esque version of the black and white variant. Does anyone know how to do that? I can easily modify the background, but the greyscale image of the 'poetree' is much more challenging.

Black & white version:



( Larger version behind the cut )

Two different colored backgrounds: (note that the tree remains in greyscale)





How do I selective tint only a portion of a particular layer's tonal range a particular color?

( Andy Warhol image behind the cut for illustration of effect I'm talking about )