I've suggested Andy Warhol-style ideas to several of you, and here's some online how-to's (with thanks to Tom, who found one of these):
A YouTube tutorial:
'Andy-Warhol-Up Your Photographs' at www.melissaevans.com
This www.alt-web-design.com tutorial:
Open Photoshop; then open any portrait image to create Andy Warhol effect.
Duplicate layer. On duplicated layer, select background and delete it.
Go to Image -> Adjustments -> Threshold (Threshold Level 135).
Fill background with colour of your choice.
Copy and paste each part of the head into a new layer and change the colors.