A friend of mine has some great data on the Leo Trio, but when printed large, he noticed that stars had red and blue edges. Sure enough, it's in the raw data and I'm not really sure what to do about it.
First, what could the cause be? He's had other images with perfectly round, white stars. I thought it might be because of a tilted camera, but I was interested in other ideas too.
Second, can I fix it? Is there some clever morphological work I could do to fix the edging for this image? I guess I'd have to apply it to the red and blue and leave the green as is.