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Old 30-09-2021, 06:42 PM
AdamJL
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PixInsight - Star Reduction Help!

Hi all

I'm starting to learn PixInsight, and working my way through some tutorials.

Right now, I'm still in the linear data phase, and I'm going to do a star reduction using MorphologicalTransofrmation after using a starmask (that I had to set to about 0.23 to get it to pick up the right stars).

However, after doing a very light (one!) pass, I see some mottling in the image

See first attachment. Picture on the left is the before, picture on the right is the after.

What causes this mottling? The star reduction works well, was it the mask itself? Is this normal and I'm only seeing it because the stars reduced fairly well?

TIA for any help
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Old 30-09-2021, 09:13 PM
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Bassnut (Fred)
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oh dear, PI is so difficult, old-school linear processing. If you have an image with good stars, its a big ask, but delete stars with starexterminator and then reinsert a clean image with good RGB stars only in PS.
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Old 30-09-2021, 11:17 PM
AdamJL
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yes it's definitely not something I'm used to (a Photoshop user for decades).
Even StarTools. as powerful as it is, doesn't make too much sense to me right now.

But this. I can't figure out what is causing the blotchiness. I think it could be the star mask I created, but I'll have to double check tomorrow. I've been trying to learn this program for 6 hours now and my brain is fried

Just a quick question, though.. when removing the stars with starexterminator, are you saying to delete them entirely, process the nebula, take another image solely for RGB stars, then layer that in Photoshop?
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Old 18-11-2021, 06:43 PM
Addos (Adam)
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'old-school linear processing'? big lol. if its still good for nasa/jpl, its good enough for me.

not sure about how to address your morphtransform question op, but a workaround ive been using that seems to get decent results for me is to do linear processing steps, then very light stretch. pull stars out with starnet, stretch dso further, then reintegrate.
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