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Autostacking using the drizzle algorithm?

Posted: Tue Oct 13, 2020 11:23 am
by timh
Hi Robin,

I am not quite sure whether this proposal makes sense but I'll try it ?

Especially since under UK skies the seeing is always the factor limiting resolution I am pushing more towards using 2x2 binning to gain sensitivity and to make the best of (e.g. Dob) short exposure times. However the price is to be heading towards undersampling ~(1.6-1.8 arc sec/ pixel).

So I wondered about stacking using the drizzle algorithm? Does it make sense (and is it even possible) to have this as an option for stacking within autostacks? Or would it then be difficult to further stack such drizzled autostacks (eg. in DSS) ? So it would be better to just collect lots of short conventional autostacks and then use the drizzle algorithm later in DSS?

best wishes
Tim

Re: Autostacking using the drizzle algorithm?

Posted: Tue Oct 13, 2020 6:49 pm
by admin
Hi,

I think the answer is that in order for it to be effective it would have to happen inside the SharpCap processing – basically you would increase the resolution of the image before you did anything else to it apart from dark/flat subtraction and debayering and then use that increased resolution for the stacking procedure and everything past that point.

In practice though, I don't think it's going to be possible – we already run into issues with the amount of memory in use when stacking with higher resolution cameras and using the drizzling approach will multiply the amount of memory required by at least four (and multiply the time taken to do any enhancements like noise reduction by a factor of four). That sort of technique is better suited to programs like DSS which can take as much time as it likes to do the alignment and stacking rather than having to do it in real time before the next frame arrives. Probably the best bet if you want to take advantage of this is to set SharpCap up to also save the raw frames while stacking and then reprocess those separately later.

Cheers, Robin

Re: Autostacking using the drizzle algorithm?

Posted: Tue Oct 13, 2020 9:48 pm
by timh
Thanks once again Robin ....yes that makes perfect sense. Maybe something for well down the road with masses of memory and when everything is a good bit faster.
Tim