i took the preceeding and messed around.
for some reason, i couldn't get any filters or anything to work on it right after i'd done it even when i changed it back to rgb. so i just closed the file and saved it.
later i opened it again and this time, it worked just like a regular jpeg. *shrug* beats me.
i duplicated the bottom layer [the preceeding one] twice. on the first duplicate layer i used filter/artistic/cutout [forgot to save settings] set to color burn at 100%.
on the second one [now the top layer] i used filter/brush strokes/accented edges set at 14, 15, 15 and set to multiply at 100%.
this gave me an interesting but rather dark image. i used a levels adjustment layer for a bit more contrast and brightness.
i created a merged visibles layer above that [making this my top layer].
to do that i created a new, blank layer above the levels adjustment layer. with that layer active, i hit ctrl/alt/shift/e. i don't know the equivalent for a mac. this gives me a merged visibles layer whilst maintaining the layers below it.
i decided it needed to be a bit more contrasty so added a contrast/brightness adjustment layer.
that gave me this result.