Author Topic: Questions about the working of the Batch Preprocessing Script.  (Read 2473 times)

Offline Allanastro1

  • Newcomer
  • Posts: 1
Hi,
I've been using PixInsight for processing for a few years now and use a combination of Batch Preprocessing and depending on my time and the image in question, sometimes the separate calibration processes.
Occasionally, when using Batch Preprocessing, for a reason I'm still trying to get to the bottom of, my flats don't fully correct for the vignetting and dust motets usually leaving slight dark regions on the final stretched image. It's not terrible but I want to find out why and eliminate it.  This seems to have occurred when I have used a flat or dark master not produced by the Batch Preprocessing script.

My investigations into this problem would be greatly helped if someone could confirm (or not) that the following statements are correct

 When using the Batch Preprocessing Script
1. The generated master dark frames include the bias signal
2. The generated master flats do not include the bias signal.
3. If I select “Optimize dark frames” this is used internally in the script to subtract the master bias from the master dark and then this new master_dark_minus_bias is scaled an used to calibrate the flats / darks. – This does not affect the saved master dark in any way and this can be used again to scale an image with a different exposure time.
4. If my dark exposures are 10minutes the program can scale them down to 5 seconds to use with the flats
5. If I had an additional series of darks taken at 10 seconds added in the script to the 10 minute exposures the script would generate two masters and use the 10 second series for the flats.

Thanks

Allan.

Offline Warhen

  • PTeam Member
  • PixInsight Old Hand
  • ****
  • Posts: 490
    • Billions and Billions
Re: Questions about the working of the Batch Preprocessing Script.
« Reply #1 on: 2017 April 05 12:33:57 »
That all sounds correct to me. I've never seen under or over correction of flats however. And believe me, I typically use pretty gnarly sky flats.;>) Obviously, good mote removal demands a very contemporaneous flats to lights matchup. Regarding vignetting, could be the nature of the flats- illumination, ADUs, etc. Thanks! 
Best always, Warren

Warren A. Keller
www.ip4ap.com

Offline tsaban

  • Member
  • *
  • Posts: 50
Clear skies!
Tahir Saban