NGC7000 nice or over processed noise?

[TiffsAndAstro]

23 minutes ago, alacant said:

Hi
Lovely shot. Especially given the short session. Oh and of course the crap gear (CG). Yes, I know exactly what you mean!

An easy way to avoid noise is to bin the data [1] before you process. Don't then though enlarge the image to the point where the noise and pixels become annoying.
There's also tilt you may want to correct. Hardly surprising bearing in mind the CG😉

Cheers and HTH

[1]
Siril > image processing > geometry > binning

Binning is something I've really not looked at, as it seems to me to just be reducing resolution. So many do bin though, there must be good reason. I'll try and have a play with it when I re process this image, thank you.

I'm hoping the tilt is down to me tightening the focus tube lock screw thing too much. Maybe.

[vlaiv]

5 minutes ago, TiffsAndAstro said:

I believe you but I'll have to research this. I've not done any blending and I think reason I avoided median filter is I didn't like it's results. I put this down to not understanding it.

Top row: baseline noise, gaussian blur with sigma 1px, gaussian blur with sigma 2px

Bottom row: median 1px, median 2px

 

[vlaiv]

4 minutes ago, TiffsAndAstro said:

So many do bin though, there must be good reason. I'll try and have a play with it when I re process this image, thank you.

That would be a good start - just take image that you already have and do bin 2x2 on linear data before you start processing it. You will notice the difference in data smoothness and it will look much more like 50% scaled version I showed you above.

[TiffsAndAstro]

57 minutes ago, vlaiv said:

That would be a good start - just take image that you already have and do bin 2x2 on linear data before you start processing it. You will notice the difference in data smoothness and it will look much more like 50% scaled version I showed you above.

Can't hurt to try. I really don't like the idea of reducing resolution, as I associate that with losing detail. But I assume with plate scale (?) and such stuff it really doesn't. 

I should be thankful we live in a era when I can just sacrifice a little time and effort to experiment and practice this stuff. No film and processing costs involved

[TiffsAndAstro]

1 hour ago, vlaiv said:

Top row: baseline noise, gaussian blur with sigma 1px, gaussian blur with sigma 2px

Bottom row: median 1px, median 2px

 

It's a strange coincidence one of my favourite YouTubers, sky story, just released a video on (not watched it all yet and, as usual it's rather above my pay grade) Gaussian blurring the entirety of the starless mask and selectively removing parts of that blur.

To remove mud and noise. Yup, mud. 

He should probably just wipe his shoes more when returning inside.

[TiffsAndAstro]

1 hour ago, vlaiv said:

Top row: baseline noise, gaussian blur with sigma 1px, gaussian blur with sigma 2px

Bottom row: median 1px, median 2px

 

This I need to try on my image for myself I think. I think gimp has the ability to do each of those processes so I can compare the results.

I really appreciate your effort. I've seen a lot of your other forum posts and they are incredibly helpful.

 

[TiffsAndAstro]

10 hours ago, vlaiv said:

That would be a good start - just take image that you already have and do bin 2x2 on linear data before you start processing it. You will notice the difference in data smoothness and it will look much more like 50% scaled version I showed you above.

i had a quick look at binning my stack and couldn't see any obvious difference. i did use it on the 45 mins i took on m57 though and did notice a difference. its still not nice to process - star net keeps the ring nebula itself in the starmask, so i might as well just no bother. it was only a test anyway so no sweat. ill put it below as its ok for what is it.

as for my ngc7000 i took the starless and starmask used for the above but this time i put the starless through graxpert. removed a small odd looking bit of gradient (though this could be information rather than noise/gradient) and a denoise. i can't recommend graxpert highly enough btw. i recombined both parts and cropped out the left hand side nasty stars. i think it has reduced alot of the noise/effect you demonstrated, above. next i will start it from scratch and bin my stacked file before doing anything else.

will also try clone tool in gimp to do something with that obvious dust mote, though as little as i can, just so the eye isn't instantly drawn to it. also a quick test with siril's star resynthesis seems to completely fix those crappy stars so im also giving that a go too

 

 

 

Edited June 3 by TiffsAndAstro

[TiffsAndAstro]

ok last upload i promise*

this should have better stars (though a bit artificial) and the dust mote isn't as eye-catching. this version looks better zoomed in, but i think the original might look better zoomed out.

i think i'll leave this image alone for a little while and come back to it with fresher eyes. 

 

 

* not really a promise

 

[TiffsAndAstro]

On 03/06/2024 at 13:40, vlaiv said:

That would be a good start - just take image that you already have and do bin 2x2 on linear data before you start processing it. You will notice the difference in data smoothness and it will look much more like 50% scaled version I showed you above.

just want to check at what point i should bin 2x2 - after stacking but before gradient removal? 

[vlaiv]

4 minutes ago, TiffsAndAstro said:

just want to check at what point i should bin 2x2 - after stacking but before gradient removal? 

Yes, maybe best place to do that would be while data is linear after stacking but before any other processing (as most processing will benefit from change in SNR)

[TiffsAndAstro]

Just now, vlaiv said:

Yes, maybe best place to do that would be while data is linear after stacking but before any other processing (as most processing will benefit from change in SNR)

cheers