Quote:
Originally Posted by vlazg
Thanks Rick, how would you combine the channels, Ha to red and the O3 to the G and B? What ratios would you use?
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Hi George,
IIRC, you're a PI user?
My usual approach these days is to match the intensities of the Ha and Oiii (using LinearFit) then make a straight HOO combine. Then I adjust the colour to taste using a combination of the Hue Curve in CurvesTransformation (brilliant for adjustments like pushing cyan to blue) and masks (mainly created with the ColorMask script) with a variety of other curves (R, G, B, a*, b*).
Some folks probably prefer to use various blends of Ha and Oiii as the R/G/B channel values to try to get closer to their desired colours with the initial combination. I used to do this but now I find I can usually push the colours where I want them to go, though it can take some effort!
The main reason I might go for an unequal HOO would be to get more Oiii to emphasise the spokes.
Here's an old Helix of mine that I'm pretty sure started as a straight HOO:
http://www.astrobin.com/68705/?image...age=3&nc=&nce=
Hope that helps...
Cheers,
Rick.