Thats’s not what I’m asking - I know darkflats are subtracted from flats. 
Siril’s Pre-processing tab accepts offset, dark and flat master calibration frames. My question is where do you load the master darkflats? The offset field?
I’m sorry but it was my answer. Load a flat sequence and preprocess with your dark flat. Stack to obtain your master flat.
Then load you light sequence and preprocess with this master flat and with your master dark.
Forgive me, but I simply don’t understand how i can “preprocess with my dark flat”.
Here I see 3 fields, offset, dark and flat. How/where do I subtract my dark flats here?
FWIW, here is the successful calibration flow when I load dark flats into the bias/offset field using SirilIC…
And here is the original calibration flow, which always fails with dark flats entered in the dark flats field…
I have blinked each and every one of my lights, darks, flats and dark flats in PixInsight to ensure there are no spurious subs where they shouldn’t be. Everything is in order.
Thanks
Yes.
But do what I say.
- Load the flat sequence
- Preprocess the sequence with your dark flat
- Stack your preprocessed flat sequence into a master flat
- Load your dark sequence
- Stack your master dark
- Load your light sequence
- Preprocess with the master flat and master dark.
That’s it.
I can’t help you with Sirilic. But if you follow what I’m saying it will be ok.
You can put your “dark flat” master in the dark field. You subtract a dark frame to a light frame, except here your light is a flat.
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I’m sorry but “preprocess the sequence with your dark flat” means nothing to me without clearer instructions (How, exactly?).
From reading this guide, it is clear to me the that in the STEP TWO: FLAT FRAMES section, the flats are pre-processed with the masterbias referenced in the “use offset” field, which makes perfect sense. All I am asking is instead of masterbias (which I don’t have) where do I source/enter/reference my masterdarkflat? Again, there is no obvious “use darkflat” field.
There appear to be 2 choices:
"use offset" or
"use dark"
Do you get what I mean with this?
Regards
After testing with “dark flat” master in the dark field, I see typical 294 starburst ampglow.
Preprocessed this time with “dark flat” master in the offset field and everything is fine. I think I will stick with this for now.
Thanks for your assistance.
Regards,
Mark
What is a darkflat? It is just a bias frame with thermal signal.
So yes, put it in the bias field.
why does it change anything between offset and dark subtractions? does it have to do with cosmetic correction?
Yes probably (or optimization)
hi,
can you check the debug option in sirilic preferences and redo the test and send me the file “sirilic-trace.log” once sirilic is closed.
can you also send me the following files:
“sirilic.log”, “sirilic-part1.ssf”, “sirilic-part2.ssf”
Hi,
Yes, of course.
PMed
I have analyzed your files: They seem normal to me.
I tried at home the darkflat process on an image of the M33 galaxy. It works until the end. I have no problem with it.
Very odd.
Definitely not working for me unless Darkflats are loaded as Offsets.
What camera are you using for your M33 test?
I use a monochrome camera cmos cooled: ZWO ASI183MM.
Hello.
Could you check if you are working in 16bit ? (check in preferences).
We have found a bug in 16bits mode with darks.
Hi,
No, l have both Siril and Sirilic configured for 32bit processing and the generated masters are all 32bit.
Only my input files are 16bit.
Thanks to some helpful fellow imagers on CN, this problem is now solved.
Problem lies with the way my camera (QHY294M) generates images.
The default configuration of the driver is to add an overscan border around all images taken, be it lights or calibration frames. Up until now, this has not been a problem with every other stacking software I have used, but Siril seems to be the exception, as it cannot handle this.
Simply disabling overscan in the driver beforehand, or batch cropping the overscan area from the edges of every subframe by exactly the same amount after the fact will solve this, and Siril will run without issue. If the crops are even a single pixel row or column mismatched, successful calibration will fail.
Now I just have the unenviable task of completely rebuilding my dark library with overscan disabled.
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