Playing around with processing to see if I can increase S/N and came across an interesting result. Not sure if this is know. Not sure also why this is happening and if there are other tricks like this to improve S/N.
Any way I look at it, the results are VERY noticeable. This process probably(guessing?) doesn't work well with the 20-50 sub stacks with long integration systems, but does with the typical cmos high # stack b/c of how drizzle works.
This is from ~425 120 sec subs with SV80+FF+ASI533 over multiple days (target hopping) with some moon light to contend with. ~14 hrs total.
Processed in PI.
1) Blink to reject any subs with significant tracking error or clouds
2) calibrate with Flats-darkflat and Darks.
3) Debayer with VNG
4) Register and generate drizzle data
5) Integrate with Generalized Extreme Studentized Deviate rejection (default settings), noise evaluate weightings, and generate drizzle data checked to update drizzle files
This produces the LEFT image (DBE only applied with auto stretch on)
6) Drizzle integrate with files produced from #1-5 with default settings (Scale=2, drop=0.9, square, pixel rejection and weighting =on).
6a) Also enable CFA drizzle
7) Downsample integrated image by factor of 2 (2x2 bin averaging) so that we are back to original ~3000x3000 pixels.
This produces the RIGHT image (DBE only applied with auto stretch on)
attached images are zoomed in autostreched crops to show the raw noise around NGC 3628. No filtering, color calibration, curves, color correction etc.