I would permit a thin pattern around the edge, but pictures where the food goes is unacceptable. Plates that are totally coloured are also out.
You should be concentrating on the food rather than some foliage, weird shapes, hunting scene or whatever, partly hidden underneath it. And coloured plates could lead to unpleasant clashes. Imagine eating some purple food from an orange plate! 
It's only a short step from coloured plates to eating off slates.