Sorting subs based on total exposure

[Rallemikken]

I shoot DSO's with a DSLR, and I'm always doing a check on my subs before stacking.  I delete subs with elongated stars, satelites and such.  And I delete those subs that are obvisouly lighter than the rest, most often caused by skies or haze, sometimes light from passing cars.

I'm in the process of mastering Siril, but untill further I also stack in DSS and Sequator. Why the childishly simple stacking in  Sequator  often beats both Siril and DSS is another topic...   Siril has excellent features when it comes to roundness of stars and FWHM, but nothing on exposure/overall lightness. DSS seems to make all decisions on its own. What I lack is an application or a script that will traverse a folder of lights, and move/delete the x% lightest of the lot. Then I can take a visual check on the remaining, and maybe run the app/script once again if I still find some frames I consider to light. I'm a Linux guy, and would prefer a bash script, but I'm willing to try anything. The best would be something that  could be used by everybody, regardless of OS and favourite stacking software.

[scotty38]

Just curious but why delete frames with satellite trails when rejection methods will sort those? You're potentially throwing away decent data....

[Rallemikken]

1 minute ago, scotty38 said:

Just curious but why delete frames with satellite trails when rejection methods will sort those? You're potentially throwing away decent data....

Nope. I live under the arctic circle, and use long scopes. Very rare with with satelite trails. And the rejection methods is discussed, both here and elsewhere. I prefer to have a as-good-as-can-be dataset before stacking, then giving the stacking software the best possible slack.

[Guest]

As sorting images according to "overall lightness" is quite subjective, only manual sorting will be usefull (IMHO).

This way, you can use the image manager (most bottom right icon), and tick/untick the wanted/unwanted images to be performed.

(it's good to be in autostretch view mode).

Then, all the ignored images will exhibit a big cross in the preview window.

[wimvb]

16 hours ago, Rallemikken said:

What I lack is an application or a script that will traverse a folder of lights, and move/delete the x% lightest of the lot

What you need is pixinsight subframe selector

[Rallemikken]

3 hours ago, wimvb said:

What you need is pixinsight subframe selector

Maybe, but I've decided to stick to open source. Gimp and Siril mainly. What I'd really want is this feature in Siril, but untill then I sort manually in my image viewer (Geeqie). A glance at the histogram, and a quick "delete" and "return" on those clearly lighter. Not overexposed, but lighter in the sense of less signal. With 200-300 subs this takes time, and it isn't very scientific. One or two bad subs can occur between good ones. Maybe I'll try to scramble a bash script myself.

[Guest]

For exemple in Siril (and without any script), you can:

-load a r_  (registered) sequence

-make a huge selection in the image, right click and "PSF for the sequence"

-then, in the plot tab, choose photometry, display backgroud. And you have a graph of the bkg for your session.

-finally, in the frame selector, you sort the images according to bkg and untick the bad once.

In a few clicks, you can discard as many frames as you want

[Rallemikken]

5 hours ago, FRed-Shift said:

For exemple in Siril (and without any script), you can:

-make a huge selection in the image, right click and "PSF for the sequence"

See what you mean. Always wondered what hid under the greyed-out dropdown that said "Registration". But this telemetry thing is a little overkill for John Doe. And if I did a "huge" selection, nothing happened, but an error message: "Current selection is too large. To determine the PSF, please make a selection around a single star". If I selected a small area around a single star, things was set in motion. The blue line started to crawl. I mostly use the OSC_Preprocessing_no_stack.ssf  and sort the subs before stacking. Maybe I can figure out a command and put in the end of that script, that does this for me? A preset selection, regardless of star density?

[Guest]

Even if you get a "light" information (see "bg" command in CLI may be?), an ssf script will not handle an if/then condition to discard or not an image.

If you want to go ahead this way, may be you could create your own script using this tuto https://siril.org/tutorials/bash-scripts/

[Rallemikken]

Maybe. But I want the subs listed by lightness, so I can use this criteria together with FWHM and roundness when I use the plot and filelist to check/uncheck subs. I can use the command line and select the PP-sequence, issue a "boxselect 100 100 200 200" followed by a "seqpsf". Does what I want, but I don't want to wait the extra time. I want to put theese commands in the script, so everything is tip-top when I resume with the stacking. But I can't.