Quote:
Originally Posted by codemonkey
What I mean by "yellow" is a filter that has a bandpass of say 480 - 700nm, and for "purple" I mean a filter that has a rejection band of say 480 - 600nm.
You can roughly estimate a similar process by:
1. Stack all RGB to create a synthetic L
2. Stack all RB to create a synthetic purple
3. Subtract the synthetic purple from the synthetic L
The output of the above operations should match your G stack. You can try it yourself using Pixel math in PixInsight if you have it.
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Of course that would work but I think
there is a signal to noise advantage in using 3 filters for colour -
in most cases RGB - just like the S/N advantage using narrow band Ha.
Also:
I notice that my RGB stacks have a better FWHM value than the L stack if they are both binned 1x1.
cheers
Allan