Andromeda Galaxy Challenge

Questions and answers about processing in StarTools and how to accomplish certain tasks.
sandconp
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Andromeda Galaxy Challenge

Post by sandconp »

I am wondering if somebody could help me process my Andromeda Galaxy using Star Tools? I have had always trouble with bringing out more of the color in the galaxy. I did watch a few You Tube Videos and I have the tiff output below. I have also included the FITS file which has already been stacked.


https://www.dropbox.com/s/5ik8gal8ysgth ... .fits?dl=0


https://www.dropbox.com/s/wbj8100cpp1fthk/m31.tiff?dl=0
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admin
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Re: Andromeda Galaxy Challenge

Post by admin »

Hi,

It appears some sort of (heavy) filter was used, so bringing out color is limited.

You really need to start using calibration frames (particularly flats; they are not optional!), as the uneven lighting/gradients were extremely strong. Amp glow is also very apparent.

The gradient/uneven lighting was very challenging to address. If flats really are not an option for you, then you will want to start off with masking out the galaxy's entire disc in Wipe. Then you will want to use the Vignetting preset and fine-tune the two Aggressiveness parameters until the uneven lighting is minimized (be mindful that Wipe's Courtesy Autodev will keep teasing you with any imperfections it can find; the real stretch after Wipe of course does not have to be identical and can be chosen to hide most of the remnants issues).

From there, you process as normal; Autodev with RoI over a slice of the galaxy, HDR to bring out some detail in the core, Decon for some further detail restoration, etc.

I used the Bi-Color preset here (Matrix HOO Duoband R: 100%R, G: 50%G+50%B, B: 50%G+50%B) with increased Saturation.

I also sharnk the star a little with the newly revamped Shrink module in 1.7. You should end up with something like this;
Stack_16bits_20frames_3600s.jpg
Stack_16bits_20frames_3600s.jpg (231.08 KiB) Viewed 989 times
Hope this helps,
Ivo Jager
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elpajare
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Re: Andromeda Galaxy Challenge

Post by elpajare »

I see a lot of photos in the Forum with this type of extremely intense vignetting. This specifically has it as you can see in the Wipe screen copy.

What can it be due to and how can it be solved?

This problem renders much of the shot useless because it is almost impossible to take advantage of the affected data
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Re: Andromeda Galaxy Challenge

Post by admin »

elpajare wrote: Sun Sep 13, 2020 9:39 am I see a lot of photos in the Forum with this type of extremely intense vignetting. This specifically has it as you can see in the Wipe screen copy.

What can it be due to and how can it be solved?

This problem renders much of the shot useless because it is almost impossible to take advantage of the affected data
It's caused by not cropping away stacking artefacts.
Your image is a textbook example actually. :)
Ivo Jager
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sandconp
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Re: Andromeda Galaxy Challenge

Post by sandconp »

Thanks for both of your input. I realize that if I took dark and flats it would of made this image a lot easier to work with. I was using a Optolong L-Enhance filter (normally used for nebulas) and forgot to put back in my L-Enhance Pro filter which is used for light pollution. I have heard from some others that I could take two different images using both filters and combine the two using Photoshop? Is there was a way this could be done in Star Tools using layering?

I will make sure that I start using flats and darks.

I had one more question. I did crop out the amp glow on the right hand side before I proceeded with autodev/dev so shouldn't that help Star Tools further down in the steps since the amp glow was removed by cropping early on?
elpajare
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Re: Andromeda Galaxy Challenge

Post by elpajare »

What destroys the image is the stacking artifacts you have that give you this terrible rectangular vignetting, you can solve that by cropping all four sides (I use a Crop of 18 pixels per side). Test it.

You will fix the Ampglow using Vignettting because it is so small. I would not cut anything, for now. Test it.

If you use any type of filter other than UV / IR you will lose colors!
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Re: Andromeda Galaxy Challenge

Post by admin »

sandconp wrote: Tue Sep 15, 2020 4:08 am Thanks for both of your input. I realize that if I took dark and flats it would of made this image a lot easier to work with.
Not only that; it will clean up signal.
I was using a Optolong L-Enhance filter (normally used for nebulas) and forgot to put back in my L-Enhance Pro filter which is used for light pollution.
Please do be aware that using filters will not allow you to recover full spectrum coloring. There is no amount of color balancing that can "restore" the missing parts of the spectrum.
I have heard from some others that I could take two different images using both filters and combine the two using Photoshop? Is there was a way this could be done in Star Tools using layering?
Combining two differently filtered stacks is not terribly useful, however combining a LP-filtered stack with non-LP filtered stack will indeed allow you to get the best of both worlds; enhanced, clean detail and full visual spectrum coloring.
Combining these is extremely simple (and should yield much better results) using the Compose module. Load the LP-filtered stack as your L (luminance) and load the non-LP filtered stack as R, G and B. Set "Luminance, Color" to "L, RGB".
Uniquely, StarTools will now process your Luminance (detail) and Chrominance (color) separately, yet simultaneously.
Use your workflow as normal. Once you hit the color module, detail and color is integrated into the final image.
amp glow
Amp glow will extend far into the image, so cropping it may reduce it somewhat but will not eliminate it.

Hope this helps!
Ivo Jager
StarTools creator and astronomy enthusiast
sandconp
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Re: Andromeda Galaxy Challenge

Post by sandconp »

Ok I processed my new M31 using dark and flats and I went back to using my L-Enhance Pro (light pollution filter) and I was able to bring out more color.

I was wondering if either of you would mind taking another crack at it? If you do, would you mind providing a tutorial video on the processes used since it would help me out immensely in learning this new tool.

I was also was trying to eliminate the blown out core of the galaxy.

https://www.dropbox.com/s/hc9g6g7cni2z9pt/M31.fit?dl=0
Last edited by sandconp on Mon Sep 28, 2020 3:21 pm, edited 1 time in total.
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Re: Andromeda Galaxy Challenge

Post by admin »

Hi,

Would you be able to give some more information on how you stacked this and what the exposure times were?

The dataset is much improved indeed! The flats made a huge difference - great work in that respect.

However, the dataset also appears to have been color balanced, while it also appears either pre-stretched or over-exposed (the core is blown out). Any idea what is going on here?
Ivo Jager
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sandconp
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Re: Andromeda Galaxy Challenge

Post by sandconp »

Hi Ivo,

Thanks for looking at my second image with using flats and darks. I used PixInsight BPP (Batch Pre-Processing to stack my lights, darks and flats. I did nothing to the lights no color balancing or pre-stretching. My exposures were 3 minutes using a gain of 200 for about an hour.

I am attaching my first light from M31 before it was stacked and you can see that the core was blown out from the very first sub.

I was hoping that there was some tool in Star Tools to tone down the blown out core.

Oh by the way, I was very surprised when I loaded in my image that I did not get a warning about any artifacts ! That is a first for me with Star Tools.
M31.png
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