Siril - Flat darks?

[BrendanC]

Hi all,

I've finally managed to get some sort of result out of Siril. I have a feeling that I'm on the verge of actually understanding how its scripts work and how to adapt them.

However, one thing stumps me: I use flat darks instead of bias frames, so how do I get Siril to do this?

If I just put my flat darks into the bias folder and let it process them, will that work?

Thanks. Brendan

[GoldTop57]

Hi - this from the DeepSkyStacker site - I assume dark flats in the bias folder isn't going to work - you could always give it a try though:

 

[BrendanC]

You're right, I don't think the maths would work. Thanks for this.

I have tried it but the results weren't great. 

There's no mention at all of flat darks or dark flats in the user guide or anywhere else that I can see. The only mention I've found close to this is here, as 'flat-dark images': https://staging.siril.org/faq/  However, it doesn't explain how to script this, and the scripts page it links to doesn't have any scripts that handle flat darks either.

I'm starting to wonder whether Siril does in fact handle flat darks at all, in which case I'll stop using it with immediate effect! It seems rather an astonishing omission.

Any more takers?

Edited August 14, 2021 by BrendanC

[GoldTop57]

I wonder if you could modify the Siril script, find the preprocess command and subtract the bias from the dark (having put your dark flats in the bias directory) then it would calibrate in the right sequence.

 

 

[BrendanC]

Nice. I'll have a go! This is literally my first time actually getting Siril to do anything so I'll have to scratch my head a bit. But I do see how that might work. Really appreciate the help, thanks.

[BrendanC]

Hmmm, looking at the script, there's this: preprocess flat -bias=bias_stacked

Then, later, there's this: preprocess light -dark=dark_stacked -flat=pp_flat_stacked -cfa -equalize_cfa -debayer

This implies to me that the flats have the bias removed before the main preprocess - which is exactly the same workflow as for flat darks, right? In which case, substituting the flat darks into the bias folder should have worked. In which case, maybe I'm doing this right.

I don't know. My head hurts. I'm going to leave this until tomorrow, but thanks for the help in getting me this far!

Edited August 14, 2021 by BrendanC

[GalaxyGael]

I think you might be right. So long as siril tests flat darks as bias (to calibrate the flats and not double process them with farms etc.) then it should work. 

No discussion on this on the siril website? 

[Ricker]

Try siril IC. This explains the process. 

[BrendanC]

@Ricker Is Sirilic (if that's what you mean) Linux only? I'm running Windows 10. POST-EDIT - I found the Windows download. Finding stuff about Siril is not easy!

@GalaxyGael I'll sound the folk out on the Siril forum, I just tend to use StarGazers as my goto resource!

Edited August 15, 2021 by BrendanC

[BrendanC]

Found these, which seems to confirm that flat darks do just get swapped out with biases: https://discuss.pixls.us/t/dark-flats-processing/23784 and https://discuss.pixls.us/t/how-to-process-and-incorporate-dark-flat-frames/19271/5

Part of the problem is phrasing: sometimes they're called flat-darks, other times dark-flats, other times darks for flats!

Right, now I need to figure out how to do a script that allocates the right darks to the right lights... 

 

Edited August 15, 2021 by BrendanC