C.M.
You can put the picture you want to use under a piece of waxed paper, pipe the outline on top of the waxed paper in piping gel (Michael's or Walmart has it in a little tub), flip waxed paper over and press lightly. The piping gel will transfer to the top of the iced cake, you can then pipe over the lines in black and fill in with stars (or just ice plain). Just remember that the picture will end up the mirror image so take that into account. Have fun.