Back to forums

Pixinsight not using flats when stacking with WBPP - not sure why

Pleiades Astrophoto PixInsight Processing Calibration Deep Sky Troubleshooting
17 replies•452 views
Harry Karamitsos avatar
Harry Karamitsos avatar
Hi everyone.  It seems I have a new problem...

I have been using PixInsight for quite a while now and I finally got the hang of it. Over the last few days I've noticed that some of my images especially the ones with Ha are not incorporating the flats. I have taken new flats a couple of days ago without any change in the equipment, and dark and bias too. It seems that WBPP is stacking, but not subtracting the flat master. I tried resetting WBPP without success. The only thing that I did in between when it was working and not was incorporate drizzle in some of the images. My image of M 33 did not incorporate drizzle but see the stacked image of Ha along with one of the flats for the Ha filter.

Anybody have any idea what I am doing wrong?



D. Jung avatar
D. Jung avatar
Can you take a snapshot of wbpp where it shows what it will use for your images? Could be many things just looking at those 2 images here
Harry Karamitsos avatar
Harry Karamitsos avatar
Here are a number of screen shots. I tried doing Ha separately, hoping it would make a difference...

drmikevt avatar
drmikevt avatar
Unfortunately, your second screen shot, the Calibration tab,  above is the important one, but the flat calibration check mark is cut off  - can you scroll the window a bit so we can see it.  Also, click on the light frames in that same Calibration tab so that we can see the calibration settings for the light frames.
Harry Karamitsos avatar
Harry Karamitsos avatar
Like this?

Harry Karamitsos avatar
Harry Karamitsos avatar
Mads Thodsen-Hede avatar
Mads Thodsen-Hede avatar
did mis read
Harry Karamitsos avatar
Harry Karamitsos avatar
Mads Thodsen-Hede:

Maybe I don't understand...
drmikevt avatar
drmikevt avatar
When you are in the calibration tab (at the top), click on the light frames, '50 frames' - click on that, so that we can see the calibration settings on the right side.  And do the same for the flats.
Harry Karamitsos avatar
Harry Karamitsos avatar
Like this?

I did make a change once I noticed that tab. The calibration frames were such a auto and that seemed not to be working, so I switched it to manual and I pointed out the appropriate flat and dark frames. I ran WBPP again all the frames were good except the Ha again. Ha seemed not to calibrate with the flats.




Rick Krejci avatar
Rick Krejci avatar
Maybe I'm wrong, but it doesn't look like your flats are using a bias or flat-dark so the flat field calibration won't calibrate properly with the lights that are.   Your flats should be picking up the bias frames you have unless they don't match in some parameter.
drmikevt avatar
drmikevt avatar
Rick Krejci:
Maybe I'm wrong, but it doesn't look like your flats are using a bias or flat-dark so the flat field calibration won't calibrate properly with the lights that are.   Your flats should be picking up the bias frames you have unless they don't match in some parameter.

He is using Masterflats, so they should already be calibrated..... right, Harry??

From the last image you posted, a few things:
 - Uncheck 'optimize darks' - that is only for when the darks and lights do not match.  Yours do.  
 - A value of 10 for Cosmetic Calibration, even though it's the default, is usually waaaaaay too strong - try a value of 25.  
 - If your flats are calibrated (with a Bias or Flatdark) you should NOT be using a Bias to also calibrate your lights - remove the bias frame; its not needed with your pre-calibrated flats

Change all of that and try again.  If that does not work, take new Ha flats since at that point everything will be set up correctly.
Helpful Concise Supportive
Rick Krejci avatar
Rick Krejci avatar
- If your flats are calibrated (with a Bias or Flatdark) you should NOT be using a Bias to also calibrate your lights - remove the bias frame; its not needed with your pre-calibrated flats

Is this correct?    I don't use darks or flatdarks, but I always calibrate light and flats with the same master bias, otherwise one would contain the pedestal and one wouldn't, which would cause the flats to not calibrate correctly mathematically
Harry Karamitsos avatar
Harry Karamitsos avatar
Ok, I'll try after work… and yes they are calibrated.
Markice Stephenson avatar
Markice Stephenson avatar
I've had this same issue without master flats that was resolved by unchecking "grouping keywords." With the already calibrated flats like yours, if they aren't recognized and linked automatically by the date/duration/filter name, then I just manually link them
Helpful
Harry Karamitsos avatar
Harry Karamitsos avatar
So, I did the above where I pointed each light collection to the appropriate flat and re-ran pixinsight. It worked!

Thank you everyone for all your help!
HR_Maurer avatar
HR_Maurer avatar
To be honest, on my latest image (not yet uploaded) i already ran WBPP three times. After the first attempt i calibrated my subs manually (i had different camera temperatures, which weren't assigned properly). After the 2nd attempt i found the costly linear defect removal is crap and produces artifacts. After the 3rd attempt i found i have to pick the local normalization frames myself…

I guess ill do it by hand this time.
Harry Karamitsos avatar
Harry Karamitsos avatar
Yeah, I never had this problem before. I kept taking flats thinking I was doing it incorrectly.