Often aerial images or raster floor plans used as working backgrounds are too dark to easily distinguish between image and model / linework. Currently, one must use an external image editing app to create lighter, desaturated, etc. versions of these images in order to work effectively with them in Revit.
Ideally Revit would have some very basic image adjustment tools built-in to make this process more streamlined. At the most basic, an image instance parameter for lightness (or "fade", whatever you want to call it) would meet most of our needs.