Allow clients to change the background fill of images in interactive designer

Currently, if I want to allow clients to have a background fill for only a portion of the template (ex. half the page) then the only way the client can customize the colour is by using a text box. This brings its own problem of having a prompt for the client to enter text, even though it is meant only as a colour fill. If the client could be allowed to modify the fill of an image in an interactive template that would solve this issue.