mask: select only faintest stars

[alacant]

1.7.421
Hi everyone

Whilist I have no trouble selecting only the brightest stars in an image, i struggle selecting only the faintest.
Any tricks and tips?

Cheers, clear skies and stay safe.
Steve

[happy-kat]

what about generate the star mask then set it up for fat stars and then subtract from mask

[admin]

What happy-kat says!

You'll notice you can throttle the auto mask generator's sensitivity by (somewhat unintuitively) reducing the Filter Sensitivity parameter.
Right above that parameter is the "Old Mask" parameter. By default it clears the old mask when it generates the new mask.
However, you can set this parameter to, for example, "Subtract New From Old". This unsets any newly found pixels, if they were already set in the old mask. You can use this to do what you want;

• Generate a mask as normal with Filter Sensitivity set to a low value. Make sure this mask includes the faint stars you're after.
• Launch the Auto mask generator again, set Filter Sensitivity to something higher, and set Old Mask to Subtract New From Old and hit Do.

You will now be left with just the faintest stars. Hope this helps!

[alacant]

Got it.
Thanks guys:)