Author Topic: Odd artifacts after integration  (Read 161 times)

Offline IamTomzo

  • Newcomer
  • Posts: 15
    • View Profile
Odd artifacts after integration
« on: 2019 February 10 19:26:20 »
Greetings,

I was processing 19 subs (5 min each with flats, darks, and bias frames) and after preprocessing, subframe selection, and integration was complete, my image has this wierd y shaped pattern that repeats itself all over the image.   I looked at each of the calibrated subs and this pattern is not present in any of them.

Do any of you have an inkling of where I went wrong here?

Thanks

Tom

Offline pfile

  • PTeam Member
  • PixInsight Jedi Grand Master
  • ********
  • Posts: 4103
    • View Profile
Re: Odd artifacts after integration
« Reply #1 on: 2019 February 10 21:00:51 »
the pattern is not in any one calibrated sub, but if you were to blink the registered subs, you'd see the pattern being traced out as you move from image to image.

they are hot pixels that have been moved around by the registration process.

all you need to do is set ImageIntegration to do pixel rejection. i don't use BPP so i can't remember if the pixel rejection controls are available under "Integration Parameters..." or not.

there are a lot of different pixel rejection modes, and the "sigma" values will need tuning, so best to look up a tutorial on ImageIntegration and try to figure out how to adjust those parameters.

rob

Offline IamTomzo

  • Newcomer
  • Posts: 15
    • View Profile
Re: Odd artifacts after integration
« Reply #2 on: 2019 February 10 21:40:01 »
Ahh - that makes sense.   I guess I am seeing my dithering there!   I will find the appropriate controls and make sure I check the right boxes next time.

Thanks

Tom

Offline Geoff

  • PixInsight Padawan
  • ****
  • Posts: 857
    • View Profile
Re: Odd artifacts after integration
« Reply #3 on: 2019 February 10 21:41:24 »
From memory I think that ImageIntegration has documentation in PixInsight. You could also check out this one
http://astrosurf.com/jordigallego/articles/Image_integration_JGallego.ppt
It’s slightly dated, but well worth reading.
Geoff
Don't panic! (Douglas Adams)
Astrobin page at http://www.astrobin.com/users/Geoff/
Webpage (under construction) http://geoffsastro.smugmug.com/

Offline IamTomzo

  • Newcomer
  • Posts: 15
    • View Profile
Re: Odd artifacts after integration
« Reply #4 on: 2019 February 10 21:46:18 »
I just went back and looked and it seems that I had not selected any pixel rejection at all.   I re-ran with windsorized sigma clipping and it is much, much better.   Sometimes I am my own worst enemy!