What is the cause for the red lines on my images?

[lycterry (Terry)]

Hello Everyone,

I am a beginner. What is the cause for the red line on my images? Any comment would be appreciated.

Frist Photo: M42 AND HORSEHEAD NEBULA
Light frame 58* 60s ISO1000
No Dark, No Bias, No flat

My setup was
Canon 6D (unmodified)
Canon 200mm F2.8 @ F3.5
CLS Filter
With SA

2nd Photo:HORSEHEAD NEBULA
Light frame 94* 40s ISO3200
20 Dark, 20 Bias, 20 flat

My setup was
Canon 6D (unmodified)
Vixen ed81
CLS Filter/
With SA

Both processing is almost the same.
I have no idea what should I do,1. I stacked in DSS 2. I adjusted the colour level with GIMP to remove the blue tint. 3.I imported to SiriL for Autostretch *3...

What can I do to improve my image? Many thanks.

Regards
Terry

[gb44 (Glenn)]

Hi Terry
Its a form of walking noise. It will calibrate out with darks/flats/darkflats /bias.

Looks like the colour will be better handled in SIRIL. Check out the youtube
https://www.youtube.com/watch?v=hIhgS3bvOy0

GlennB

[lycterry (Terry)]

Thank you, Glenn. Will definitely have a look.

[Mickoid (Michael)]

Terry, another factor that would be creating odd colours and patterns in your processed images will be colour saturation. It looks like in your efforts to achieve the colours that appear in these objects most commonly seen, you have over saturated the image to the point where it has revealed all the gradients that may have otherwise been hidden under less saturation. Your camera is unmodified, so it will not capture colour the same way a modified camera will, especially in rich Ha regions.

[leon]

Hi terry, I think Michael might have nailed it, tone it down a bit and you will see the difference and as well, and said, un-modified cameras do capture deep space differently.

Stay with it though, and with a few tweaks here and there you will soon be mastering it.

Leon

[JA]

Originally Posted by lycterry

Hello Everyone,

I am a beginner. What is the cause for the red line on my images? Any comment would be appreciated.

A few possibilities come to mind, but it would be good to know if the red squiggly lines in the first image or dark squiggly lines in the second image are in any way present in the subexposures, flats, darks and bias frames. You may need to increase exposure in say Photoshop to hunt for them. That is the first thing i would do to track it down, then possibly you could try another image stacking program other than DSS? Maybe Sequator or other just in case it's some sort of weird stacking artifact?

As already mentioned by Glen above, it could be a sort of walking noise, which can result from various fixed pattern noise in the sensor, which would likely be made worse at higher ISO or with any PA errors (even though yours seem Ok in that respect.

Also did you dither your images? That can have a significant effect on improving fixed pattern noise.

Give all that a try - especially checking the individual subs, flats, darks, bias frames and trying another stacking program.

PS: if the problem really turns out to be imbedded in the data, rather than resulting from the processing, then some patience and work with the Photoshop or GIMP equivalent of the clone tool is really your only option to paint out the squiggly red and dark lines.

Best
JA

[Nikolas (Nik)]

There is walking noise and hot pixels as well as oversaturation
In DSS when you stack use sigma kappa clipping, it's in one of the stacki settings.

As your acquisition improves try dithering your images to eliminate walking noise.

[mswhin63 (Malcolm)]

I have had plenty of these occasionally, Guiding should use Random dithering, also I had accentuated red trails from using Maximum instead of Sigma Clipping.

Sigma clipping @ 2 should get rid of these red bits which in my setup was trailing Hot Pixels.

[lycterry (Terry)]

Thanks, Leon and Michael. Thanks for pointing it out. I must have over adjusted the color level with GIMP. The walking noise starts showing up when I adjusted the colour level for the 2nd / 3rd time. The more I adjusted, the more is the walking noise.

I then used what Glenn had suggested,

https://www.youtube.com/watch?v=hIhgS3bvOy0

I tried the script, OSC_Preprocessing, but failed. Not sure if there is some problem with my flat images.

21:29:35: MAD is null. Statistics cannot be computed.
21:29:35: Normalization failed. Check image 1 first.
21:29:35: Execution time: 406.74 ms.
21:29:35: Setting CWD (Current Working Directory) to 'D:\Astro\19022022 2 - Copy'
21:29:35: Script execution failed.


I ended up using the script, OSC_Preprocessing_WithoutFlat, did a Colour Calibration and an autostretch ( It is so powerful, 1st time to use ) and the image has no walking noise and looks a lot better.

Thank you.

Regards
Terry

[lycterry (Terry)]

Hi JA, Nikolas and Malcolm,

I didn't dither my images, but I will definitely have a look too. Will also try sequator, Sigma clipping as well.

Everyone is so helpful.

Thanks a lot.

Regards
Terry