What do I use to fill in a picture on a cake? For instance, you would thin your royal icing for a cookie...would you thin your buttercream for a cake?
I used buttercream for filing in the image on the cat. I just zapped it in the microwave for a few seconds. There's probably other ways to do it, but for what its worth; that's my two cents.
Well my only thought is to find out if the picture has out lines through out it? If it were out lined like with maybe a bc transfer than yes you could do it but other wise it would run and not be able to set.