best way to reduce very noisy color noise/rgb noise in a photo? (gimp)

[realflow100]

What are some good ways to combat high noise in a photo to make it smoother without losing any details or making any details get smoothed out.
what ive been doing is processing the image as normal but separating the shadows mids and highlights by using levels and putting them on different layers. and then processing them separately. doing more aggressive noise reduction in the shadows.
but finer and less to mids and highlights. and more fine tuned to each layer. so I get the smoothest background least amount of noise and most detail in the highlights. and applying contrast brightness saturation and adjustments independently to shadows mids and highlights

Is there a better way to do it?
i'm using gimp by the way to edit my processed photos. its not the best but its free

[yobbo89]

i can't help you with your program, but typically in my processing routine in pixinsight i do a bit of sharpening of the high signal areas with a mask,and blur the low signal areas that are noisy ie the background .

[realflow100]

I'm not sure how to uses masks! only simple layers and layer effects like add subtract multiply ect.

I dont have much data to work with. its just a few large bloated stars and a faint fuzzy noisy galaxy core (andromeda)

heres what i've attempted so far

First picture is original fully processed with lots of noise

second picture is a strange noise reduction method ive tried.

[JayTee]

When you process your images are you using Deep Sky Stacker (free software) and providing this software with darks, flats, and bias frames along with your light frames? If not, then this is the first step to getting brighter, more detailed images.

[STEVE333]

There are some YouTube tutorials by Doug German. They are aimed at using Photoshop, but, Gimp is so similar to Photoshop that you should be able to follow along in Gimp. A link to the first in his series of 6 tutorials (Part 1 - Part 6) is below.

https://www.youtube.com/watch?v=Ke3iO9d2Qw8&t=2s

He has several other YouTube tutorials on image processing also.

Hope these are useful.

Steve

[realflow100]

No I use gimp for processing the image. I dont process with deep sky stacker. it produces horrible images so I only stack with it and save image without any adjustments. and the light pollution color gradients clip all the detail into black if I do it that way.

I only use dark frames and light frames.
I haven't gotten flats to work because of my light pollution gradients problem it always over comepensates. or just doesnt come out right. i dont have a good way to do it.

This particular image is especially noisy because I had to resize it to like 1/8th resolution to get it to stack at all. because of how big and bloated the stars were!
and its still super noisy because i only took a few short exposures. i'm surprised i managed to even get the satellite galaxies around andromeda with this much noise anyways

[realflow100]

I superglued a bubble level onto my camera right above the viewfinder. it first there perfectly and is flat and level there.
after I get the tripod as level as I can then I can tilt my camera upwards. then angle it left/right on the platform to get it centered while tightening it down. so it aims perfectly straight up

[Baskevo]

No I use gimp for processing the image. I dont process with deep sky stacker. it produces horrible images so I only stack with it and save image without any adjustments. and the light pollution color gradients clip all the detail into black if I do it that way.

I only use dark frames and light frames.
I haven't gotten flats to work because of my light pollution gradients problem it always over comepensates. or just doesnt come out right. i dont have a good way to do it.

This particular image is especially noisy because I had to resize it to like 1/8th resolution to get it to stack at all. because of how big and bloated the stars were!
and its still super noisy because i only took a few short exposures. i'm surprised i managed to even get the satellite galaxies around andromeda with this much noise anyways

Light pollution shouldn't have any affect on your flats. I would recommend getting those down first, because it can make a massive Improvement

[realflow100]

I meant light pollution has a big effect on the LIGHT frames. meaning impossible to fix background gradients. wavy ripples and random things that flats wont fix.

[Graeme1858]

I meant light pollution has a big effect on the LIGHT frames. meaning impossible to fix background gradients. wavy ripples and random things that flats wont fix.

Flats will however, fix vignetting, dust bunnies and sensor artifacts. If you add some to the DSS stacking run then Gimp will have a better chance of processing your final image.

Regards

Graeme

[realflow100]

ive never had any luck using flats.
Always overcompensates. or just doesnt help.

i basically make my own flats from the stacked image by lightly processing it and then blurring the whole image with a duplicate layer. and use healing tool to remove any very bright stars or objects. set to 50% transparency on subtract mode. and then play with brightness and contrast and saturation to flatten the image out. repeating if neccessary
Doing this also gets rid of light pollution gradients a significant amount. which is what i have more of an issue with than flats.