PI beginner, want to stack images saved in JPEG

randomcoolzip

New member
Oct 10, 2015
2
0
I'm working my way through the wonderful 12-part YouTube tutorial, which is making PI comprehensible for the first time. I have a series of subs of M51 that I took a few years ago. These were saved as JPEG files because I forgot to make my Nikon DSLR save the pictures as raw files. Should I convert the JPEGs to some other format before I start subtracting dark frames, extracting background, aligning, stacking, and so on? Do I need to de-Beyer these files if they're already JPEG? I can't tell from the tutorial because he starts from a raw format.
 

pfile

PTeam Member
Nov 23, 2009
6,381
217
you don't need to debayer them and calibrating them is sort of a nonsense operation since the process of creating the jpegs debayers, brightens and compresses the files. this really destroys the bias and darks.

you might be able to get away with flats however flats need to be calibrated to work properly and so you have the same problem.

rob
 

randomcoolzip

New member
Oct 10, 2015
2
0
Thanks so much. And of course the dark frames I took were also JPEGs. So it sounds like there's not much use doing anything with them. I do need to do something about subtracting out the skyglow that's in these pictures. I think that's a job for dynamic background extraction, if I understand the lingo. And then alignment and stacking. Any other suggestions? You've been really helpful.

In fact, given the sky conditions that are typical where I live (rural Massachusetts), I'm going to need to get good at removing background skyglow.
 

pfile

PTeam Member
Nov 23, 2009
6,381
217
that's correct, DBE. however it's probably easier to just register and then integrate all your frames and apply DBE to the master light. there is a method of doing batch operations in PI but due to it's 'dynamic' nature DBE does not work right with that method (ImageContainer). ABE does work with ImageContainer but it's a super pain to get the settings all tweaked so that they are applicable to all of your subs. much easier to do it on the single integrated master light.

rob