While looking forward some older stuff to reprocess a couple of images to put back on astrobin, I found some extra subs I never was that happy with. They were pretty noisy, and had some weird banding I haven't seen before or since.
In the end I managed to get rid of the banding playing round with masks, pixel math and curves transform in pixinsight. It came out ok in the end, not sure if the colors are right, and there is still plenty of noise around the galaxy.
22 x 60sec ISO400 unguided
20 flats, darks and 40 bias
You can still just make out the horizontal bands, they aren't in the usual place for this camera and the darks from that night nor any other seemed to show anything in the same place either.
Nice recovery and restoration Elliot. Have you tried just ditching the darks and use the flats and bias only? It's possible that the darks are adding noise rather than subtracting it. I only say this because you said that the pattern noise does't line up. It might be worth a shot to see if it makes any difference.
Thanks. I have a couple of ideas on whats going on - either I somehow stored the images rotated 180, which would line the banding up with where it normally is, or it's to do with taking darks in high temperatures. These were all from 30+ nights.
Either way it was a good exercise in making pretty specific masks with pixel math.
