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Does anyone know what is producing this streaky pattern on this image of Andromeda. It is more prominent on this half of the galaxy. This was stacked using WBPP script in IP. This image was stretched a bit more brutally to show the pattern but it is still obvious in more carefully done processing. It is present in the integrated image from the start so not introduced by the post-processing. Camera is an ASI533MC Pro. Asking for a friend (no really - this time I am).
Streaky artefact on Andromeda
Engaging
Andrew Rambaut · Dec 19, 2025 at 06:20 PM
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How often was the mount dithering?
Did you use calibration frames ? Are they adequate as regards sensor temp/gain/ duration?
I remember having observed this with hot pixels that do not register due to guiding shift from an image to the other and thus may create this kind of artefacts. Pointing shifts linearly so that drift creates lines-like pattern.
Helpful Insightful
bigCatAstro · Dec 19, 2025 at 06:26 PM
Andrew Rambaut · Dec 19, 2025 at 06:20 PM
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How often was the mount dithering?
Good question - I will find out.
looks like walking noise, which goes away if you dither properly
this is what one of my comet stacks looked like without dithering (533mc-p), ended up never publishing the processed image
this is what one of my comet stacks looked like without dithering (533mc-p), ended up never publishing the processed image
Oscar H. · Dec 19, 2025 at 09:30 PM
looks like walking noise, which goes away if you dither properly
this is what one of my comet stacks looked like without dithering (533mc-p), ended up never publishing the processed image
I have not seen this before a I have always had dither on. I am trying to get my head round what it is - presumably a fixed pattern of noise on the sensor which slowly drifts across the image over the entire imaging time because of a slight drift in the mount (not enough to affect individual frames)? The registration aligns the image and stars but now the noise pattern is streaked?
Looks like walking noise that has been run through BlurXterminator.
None of my images are dithered, not a single one. I don't have walking noise.
Jon Main · Dec 19, 2025 at 10:18 PM
Looks like walking noise that has been run through BlurXterminator.
Thanks - definitely been through BlurXterminator but he wanted to know what generated it in the first place. I will let him know.
andrea tasselli · Dec 19, 2025 at 10:20 PM
None of my images are dithered, not a single one. I don't have walking noise.
I would guess that walking noise is the product of not dithering and not using good calibration frames?
alpheratz06 · Dec 19, 2025 at 06:33 PM
Did you use calibration frames ? Are they adequate as regards sensor temp/gain/ duration?
I remember having observed this with hot pixels that do not register due to guiding shift from an image to the other and thus may create this kind of artefacts. Pointing shifts linearly so that drift creates lines-like pattern.
Interestingly the first image he sent did have bright coloured streaks which I assumed were hot pixels and suggested he did new darks. That got rid of the bright pixels but doesn’t seem to have got rid of the more subtle effect.
andrea tasselli · Dec 19, 2025, 10:20 PM
None of my images are dithered, not a single one. I don't have walking noise.
I think at the root of it, it really depends on your set-up, how well you’ve polar aligned, length of subs, and if your calibration frames were taken correctly. I dither because it works for my set-up and light polluted skies.
I used to get walking noise (I didn’t understand it at the time) when I used a stock DSLR, a Celestron C8-N, and CG5 mount. Granted, since the DSLR wasn’t cooled, that may have attributed heavily to the walking noise.
I wonder if the darks were taken at the same temperature and for the same amount of time as the lights.
Well Written Helpful Respectful Concise
bigCatAstro · Dec 19, 2025 at 10:49 PM
andrea tasselli · Dec 19, 2025, 10:20 PM
None of my images are dithered, not a single one. I don't have walking noise.
I think at the root of it, it really depends on your set-up, how well you’ve polar aligned, length of subs, and if your calibration frames were taken correctly. I dither because it works for my set-up and light polluted skies.
I wonder if the darks were taken at the same temperature and for the same amount of time as the lights.
Any of these things are a possibility. The stars look sharp so any drift must be very slow (which would make sense as the streaks are over the entire imaging time). I don’t think the total integration time is that long so it is probably stretched such that a very low intensity effect is amplified.
I will feed all this back - thanks for the advice.
Walking noise, can’t save this one :-)
From now on use dithering.
CS
I do use dithering so I have never seen this effect before.
Well Written
OK thanks to everyone who responded - to summarise: likely ‘walking noise’ - not a phrase I had heard before but then I hadn’t seen the effect before. Product of fixed noise from the camera slowly drifting (or rather the image is drifting but that is brought back into registration so it looks like the noise is drifting). Can be ameliorated by dithering so the noise jumps around and just becomes random noise per sub and/or good calibration frames to remove the fixed noise.
Does that sound about right?
Helpful
That's about it.
andrea tasselli · Dec 19, 2025, 10:20 PM
None of my images are dithered, not a single one. I don't have walking noise.
Same. And I've only seen it once in my output.
Tom
Tom Marsala · Dec 23, 2025, 05:21 PM
andrea tasselli · Dec 19, 2025, 10:20 PM
None of my images are dithered, not a single one. I don't have walking noise.
Same. And I've only seen it once in my output.
Tom
Lucky duck!
bigCatAstro · Dec 23, 2025, 05:28 PM
Tom Marsala · Dec 23, 2025, 05:21 PM
andrea tasselli · Dec 19, 2025, 10:20 PM
None of my images are dithered, not a single one. I don't have walking noise.
Same. And I've only seen it once in my output.
Tom
Lucky duck!
Don't I know it, haha!
The young lads nowadays are lucky as they have so many good cameras on hand compared to us who started all this astro stuff more then >20 years ago and started to use our digital cameras and knew about walking noise… which was very common in those days…
The Colour chips in the astrocameras from nowadays are not that different from the color chips in the Prehistoric DSLR’s we used many years ago… and so walking noise is somthing normal and the ones who do not have it is due to, as it was already explained, dithering the images…
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Is There Any Method To Get Rid Of Artifacts?
Unprocessed Image Of Andromeda Galaxy https://imgur.com/a/98IUK1g Hello and welcome. I'd like to ask everyone who is using Seastar or any method to get rid of all of the artefacts in their deep sky images. I have a pretty good image I made with m...
Addresses streaky artifacts on Andromeda images; directly relevant to author's problem.