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Tool SCNR best uses

Processing Deep Sky Galaxy
6 replies•265 views
Riccardo Civati avatar
Riccardo Civati avatar
Hi everyone

I ask for opinions on the use of scnr.

Especially in the deepsky field with images of galaxies with sky background.

many apply scnr at 100% after the color calibration has been performed, in this way however the sky background becomes purple due to the reduction of the green contribution.
I don't think this mode is the most correct

I currently use a luminance mask in order to perform a 100% scnr only on galaxies and stars and I perform a reduced scnr to have a uniform sky background median between the 3 colors.

in your opinion is it the correct way? How would you do it?

CS
Riccardo
V avatar
V avatar
I'd use SCNR in the same way that I'd cheat on my wife. Never.

It's a destructive process that ruins your image (That goes for both ends of the analogy).

Simply put you shouldn't use SCNR if your SNR is high enough, as it will degrade actual pixel data that is present, you should just take the green channel and tone its mid-band back a little bit, then recalibrate the background.
andrea tasselli avatar
andrea tasselli avatar
50% to 20%. No need to apply a luminance mask (which I wouldn't have anyway, most of the times). But I'm shooting OSCs so a green background is kinda expected.
D. Jung avatar
D. Jung avatar
I think there are better ways to control the final color in the image, but at least for me, the tools that PI offers are a bit behind from what you can find in "normal" photo editing software. 
I find myself using SCNR as last resort if modifying the tone curve or histogram just don't do the trick, usually at 50%. I wish they had the color control options from rawtherapee in PI

Tobiasz avatar
Tobiasz avatar
I'd use SCNR in the same way that I'd cheat on my wife. Never.

It's a destructive process that ruins your image (That goes for both ends of the analogy).

Simply put you shouldn't use SCNR if your SNR is high enough, as it will degrade actual pixel data that is present, you should just take the green channel and tone its mid-band back a little bit, then recalibrate the background.

This.
Tony Gondola avatar
Tony Gondola avatar
….what is SCNR?
Bob Lockwood avatar
Bob Lockwood avatar
Tony Gondola:
....what is SCNR?

If you end up getting PI, it's a tool that tries to remove green.