I want to transfer a Star Wars picture to a cake. Is there a way to do this?
I don't want it to be a "plaque", just a color picture on buttercream frosting. or mmf.
I'm pretty sure I've seen this in bakeries.

oooh, i also would like to know if and how this can be done.

You could do a FBCT (frozen buttercream transfer) or an edible image.

Oh my goodness - an EDWARD Cake! How on earth did you do that?

There are several way this can be done.
1) Frosting sheet pic
2) Frozen b'cream transfer
3) Chocolate transfer
4) Color flow drawing
5) piping in icing

The fastest way is #1 Some grocery store bakeries or cake supply shops will make an edible picture for you. The cost is usually around $5-10 per picture.
Others have already explained FBT & CT.
Color flow is similar to those, except it is done with royal icing and allowed to dry. It hardens as it dries.