I apologize for posting a question and then waiting 3 days to check for replies! Thanks to every one who had suggestions and info.
I'll try some of your techniques. I was already
using the "similar color" background, but hadn't thought about complete pixels. I've been used to the raster images that naturally use complete pixels.
It still seems simpler to take the raster image into Imageready and crop it, but then I get a certain loss to the image quality, so I'll just have to streamline my Xara techniques!

Gary V.
The more I learn, the more I realize how ignorant I am!