Author Topic: Andromeda Hates Me - Observatory Images  (Read 2351 times)

Offline CepheidSoul

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Andromeda Hates Me - Observatory Images
« on: 2016 October 13 08:25:13 »
Hello PixInsighters
I took these images in November of 2015 at our Observatory at Simon Fraser University, British Columbia, Canada, and have been wrestling with them since. I unfortunately cannot take new images with the setup I had at the time and am trying to salvage these ones.
When colour combined, the image shows really strange colouring. I think the problem was with the flats.

Because the image is full of nebulosity, the DBE and Background Neutralization tools don't seem to be working. However, I am able to get the colours to correct fairly well with ABE at Function degree 2 on the master lights, them combine, colour calibrate. The stars' true colours show up this way, but the image has a magenta wash over the entire thing that I cannot seem to account for.

I've been working on this now on and off for 6 months now and now I just feel like I'm beating my head against a wall. I would really appreciate any help anybody could give. Below are the links for the calibrated, registered, drizzled, and cosmetically corrected LRGB  light masters. Basically I'd just love some input on how I might be able to save the images.

Total exposure time is just over 5 hours. 70cm scope. FLI CCD Monochrome camera cooled to -20C.



https://drive.google.com/open?id=0B4YOsGYDH_-jZVFZMFZSc3F6SnM
« Last Edit: 2016 October 13 08:38:46 by CepheidSoul »

Offline pfile

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Re: Andromeda Hates Me - Observatory Images
« Reply #1 on: 2016 October 13 09:31:32 »
i saw this on reddit last night and gave it a try - when i got to the end i could tell that there was a circular area in the middle of each frame that was brighter than the rest of the frame. i think this is probably due to the flattening issue you mention.

after that i kind of gave up. i'm sure its possible to get somewhere with this now that its known that there's a flattening gradient in the image, but i didn't try...

rob

Offline CepheidSoul

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Re: Andromeda Hates Me - Observatory Images
« Reply #2 on: 2016 October 13 16:27:25 »
Thanks for trying!

Offline Alejandro Tombolini

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Re: Andromeda Hates Me - Observatory Images
« Reply #3 on: 2016 October 16 15:31:38 »
Indead is very complicated, something should be wrong in the flats. A possibility could be to try calibrating the image without flats (if motes dust allow that) and maybe easier to deal with the image.
I made a try with DBE to solve the problem and tried to calibrate color as much as was possible.
Attached are the process icons used.
Let me know if it helps.

Saludos, Alejandro.

Offline CepheidSoul

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Re: Andromeda Hates Me - Observatory Images
« Reply #4 on: 2016 October 19 09:03:45 »
Hey! Thank you! Thank you for taking the time to do this and for sharing the process icons.

That version looks pretty good. I have been trying to achieve similar results with ABE as I found DBE wasn't doing it for me but I will give this a try. At what stage did you apply the DBE? While probably not ideal, I've been applying the ABE at the non-linear stage otherwise I found it did strange things to the image.

Again, thank you so much for putting the time into this.

-M


Offline Alejandro Tombolini

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Re: Andromeda Hates Me - Observatory Images
« Reply #5 on: 2016 October 19 09:45:16 »
Hi, good to know it was useful.

At what stage did you apply the DBE?

I have applied DBE on the linear stage of both image (L and RGB). The attached image shows the workflow of the process. At left are the processes applied to the L image, at right the processes applied to the RGB images and bellow at the center the processes applied to the mixed image.

Saludos, Alejandro

Offline msmythers

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Re: Andromeda Hates Me - Observatory Images
« Reply #6 on: 2016 October 19 09:51:59 »
Alejandro

I was wondering what made you decide to use GREYCstoration instead of one of the other tools?


Mike

Offline Alejandro Tombolini

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Re: Andromeda Hates Me - Observatory Images
« Reply #7 on: 2016 October 19 16:18:07 »
Hi Mike, even when GREYCstoration is not a tool commonly used, it works well when there is high signal with different types of structures, for example dark nebulae and bright nebulae or transitions with stars.
It is also easy to use. Note in this example that I have used default values, only varying a little the sharpness to control the anisotropies and also with a Lightness mask to protect areas with high snr.
Maybe would not be the first tool of choose to work on a noisy and dark background as it could be more tricky to obtain a satisfactory result.
See the attached image with the before and after in this image.
Saludos, Alejandro.

Offline msmythers

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Re: Andromeda Hates Me - Observatory Images
« Reply #8 on: 2016 October 19 16:38:45 »
Alejandro

Many thanks for the explanation and example as always. I will have to give it a try sometime.


Regards

Mike

oh yeah, I don't know if there are many of us using TGVInpaint but I find it a great tool.