Not sure if this is just Halo's or Noise? Any ideas how I can fix this on Pixinsight?

[Durrani84]

 

Hi Everyone:

I just recently modded by DSLR and really happy to see much more red in my images. I tried taking a picture of the Heart nebula. I have an 8 inch 3.9F Orion Newt, powered by ASI Air Pro on a CEM 40 mount.

I am really happy with the final picture, but im a novice on Pixinsight. If I zoom into the stars, I see like long strands over the stars (like greyish roads?)  I'm not sure what they are. Are these artefacts of some kind?

Any ideas on how I can create a clearer picture between the stars?, would really be appreciated.

Thank you in advance!
 

Best regards,

 

Kam

[alacant]

Hi

Love the image:)

A few hands on before-you-process ideas from our 208mm f3.9 which saved us a lot of head scratching and should help clean the mottle...

Lose any dark frames.

Dither between exposures and stack with a clipping algorithm.

Remove the mirror clips and instead, fix the mirror using neutral silicone sealant at the same points you find cork/felt/nylon to glass.

Cut the secondary end of the focuser barrel if it is protruding into the light path. It most likely will be.

Cheers and HTH

Edited November 2, 2021 by alacant

[vlaiv]

1 hour ago, Durrani84 said:

If I zoom into the stars, I see like long strands over the stars (like greyish roads?) 

Those are just denoising artifacts.

Try processing your image without denoising algorithm applied.

In a busy star field denoising can blur out faintest of the stars and if they are ordered in chains - that starts to look like strand of light.

You might be slightly over sampling as well.

[Durrani84]

 

Thanks @alacant: Really appreciate your feedback..Im not very technical so I dont think I can comfortably make many of those changes  but I do dither and I will try skipping Darks!

@vlaiv, Thanks I do quite at a bit of noise reduction on Pixinsight so I could be that...but If I leave it the picture will be quite noisy... I am thinking of not running noise reduction on Pixinsight and use Denoise AI instead.? Any suggestions on what I could do instead?

Thanks,

 

Kam

[vlaiv]

1 hour ago, Durrani84 said:

Any suggestions on what I could do instead?

Well, one of great skills of processing is to push the data only as far as it will let you.

If image is too noisy - then you probably stretched a bit too far.

There is nothing wrong with having a bit of noise in the image. Also - knowing how much noise can be denoised without significant impact on the image quality is another skill that is worth learning.

In the end - you should do masked denoise.

Noise levels are intimately tied to signal levels in the image - you should denoise only fainter parts of the image. You do that by creating layer mask - using luminance of the image as mask itself.

Here is an example - this is lum layer of NGC7331 from couple of years ago:

That is streched as data will let me.

If I try to stretch a bit more - look what happens:

Background noise starts to pop up.

Can I deal with it? Well, I can denoise, sure, but look how softer image becomes:

Let's mask things - and apply denoising only to background:

This is my layer mask:

I'm using inverted mask here - intensity - so where it is bright - denoised version will be shown. In the end, blended it looks like this:

In the end, I just restore black point and

You can also do above mask trick with sharpening. You can really only sharpen high SNR areas - and if you sharpen the background - noise pops up. Do inverse masking this time - so that background is from smooth image and detail is from sharpened image.

There you go - stars and detail pop up a bit and noise and background is held at bay.

[Durrani84]

@vlaiv, Thanks for your input really appreciate it. I have started to run initial noise reduction on Pixinsight and then finish off with Denoise Ai which works really well.

Best regards,

K