Hi,
I have developed another possible reason that would be terrific if someone could comment on. Attached is a JPG of a star through a blue filter. There are three images attached togeather: no processing, bias sharpening only, and bias/deringing. The square area around the star following bias application looks a bit like the diagonal orange artifacts on the previous submitted images. Could what I be observing is differential application of de-reinging on each of the channels. Just a thought.
Don