Inserting an image into an ODS cell

Hi, is it possible to insert an image into an ODS cell like you can in ODT text?
I have tried using the same method but this does not seem to work.
We have a Red, Amber, Green rating system, all I want to do is colour a cell to show what its rating is. I thought the easiest way would be to drop an image in the cell, but I can't get this to work. Is it possible or is there any way to specify the background colour of a cell based on the data for that row?

Thanks, Paul