mask: select only faintest stars

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alacant
Posts: 211
Joined: Mon Jan 25, 2016 7:03 am

mask: select only faintest stars

Post by 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
Posts: 372
Joined: Sun Feb 01, 2015 11:31 am

Re: mask: select only faintest stars

Post by happy-kat »

what about generate the star mask then set it up for fat stars and then subtract from mask
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admin
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Re: mask: select only faintest stars

Post by admin »

What happy-kat says! :text-yeahthat:

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!
Ivo Jager
StarTools creator and astronomy enthusiast
alacant
Posts: 211
Joined: Mon Jan 25, 2016 7:03 am

Re: mask: select only faintest stars

Post by alacant »

Got it.
Thanks guys:)
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