Does anyone process subs before stacking!!??

[dugnsuz (Doug)]

Hello all...
Prior to stacking a set of subs in Images Plus, I will check each sub for focus and tracking errors.

Do any of you perform a pre-stack regime on each sub?
Like a sharpen or star minimization?

Wondered if there may be benefit in doing this?

Cheers
Doug

[RB (Andrew)]

No, no sharpening or anything else on subs pre stacking.
Only check for tracking errors/focus etc.
Stack the calibrated frames then proceed with post processing the stacked subs.

[leon]

No Mate, other than chucking out the bad ones, leave them as they are, well that is what I do.

Leon

[Dennis]

Just Darks and Flats for each sub frame before the final Align & Combine.

Cheers

Dennis

[centroid (Dave)]

Yep, as the guys have said:

Calibrate all subs first (dark and or flat subtraction etc), align, then finally combine.

All processing is then done on the resulting combined image.

In the case of 'Single Shot' colour images:

Calibrate, de-Bayer (colour synthesis), align, combine, then process.

Dave

[[1ponders] (Paul)]

Pre-processing of subs via sharpening or deconvolution!!!! Quick everyone, grab him!! He is a heretic and must be burned at the stake!!! Outrageous!!



Generally no Doug, but if you are only doing it for the effect and not trying to obtain "scientific info" then give it a go, you never know. Keep the decon very light though.

[h0ughy (David)]

Originally Posted by [1ponders]

Pre-processing of subs via sharpening or deconvolution!!!! Quick everyone, grab him!! He is a heretic and must be burned at the stake!!! ..................

is this an example of HOT pixels

[TrevorW]

Theres another issue here as well, such as darks and flats what need is there to do these on the mount at the same time you do the lights if you can simulate the temperature etc then these can be done indoors.

Likewise DSS will stack images of different exposures and ISO settings. So Dougie if at the end of the day it improves the resulting image why not do it in my opinion but how should I know I'm just a novice.

[dugnsuz (Doug)]

Reason I started this thread was because I had the vague recollection of a thread/post in which jase described a pre-processing regime.
Might be barking up the wrong tree or mis-remembering(!), but it stuck in the back of my mind.

Doug

[kinetic (Steve)]

Originally Posted by TrevorW

Theres another issue here as well, such as darks and flats what need is there to do these on the mount at the same time you do the lights if you can simulate the temperature etc then these can be done indoors.

Me, being a relative novice compared to some of the imaging experts here
Trevor, I wouldn't take this as gospel , but....

I do believe that it's a good idea to do the darks/flats at the scene of the
crime so to speak purely because the environment that is generating the
electronic noise in your webcam/ dslr /induced into any cabling etc is
better compensated and eliminated by a perfectly matched sub taken
in the same noise environment.
That's the experience I have had with years of modified webcams anyway.

regards,
Steve B.

[jase (Jason)]

Originally Posted by dugnsuz

Reason I started this thread was because I had the vague recollection of a thread/post in which jase described a pre-processing regime.
Might be barking up the wrong tree or mis-remembering(!), but it stuck in the back of my mind.

Doug

Yes Doug.
Apply darks, flats and bias frames (the latter is required if you're scaling your darks). Then, hot and dead pixel removal, this cleans up what the darks may have left behind. Register/align each sub (per channel), then blink them. This is important as it allows you to evaluate the sub quality along with any potential discoveries (we are forever hopeful). Remove the subs that show less desirable features i.e. star FWHM or HFD too high. With the remaining excellent subs, stack/combine them. No an advanced routine, but something that has stuck with me over the journey of imaging.

[dugnsuz (Doug)]

Originally Posted by jase

Yes Doug.
Apply darks, flats and bias frames (the latter is required if you're scaling your darks). Then, hot and dead pixel removal, this cleans up what the darks may have left behind. Register/align each sub (per channel), then blink them. This is important as it allows you to evaluate the sub quality along with any potential discoveries (we are forever hopeful). Remove the subs that show less desirable features i.e. star FWHM or HFD too high. With the remaining excellent subs, stack/combine them. No an advanced routine, but something that has stuck with me over the journey of imaging.

Cheers jase, glad you found your way to this thread to clear this up.
Thanks
Doug