Achieving Color in Galaxies

Questions and answers about processing in StarTools and how to accomplish certain tasks.
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midwayexpress
Posts: 69
Joined: Sat Jan 12, 2013 9:42 pm

Achieving Color in Galaxies

Post by midwayexpress »

I have been evaluating image processing software to go with my new setup. Recently I discovered that I was still having problems with DSS due to the file save bug. I finally resolved the problem and learned through the help of the folks at cloudynights how to achieve color in my galaxy shots with photoshop. Now I would like to learn how to achieve the same effect with Startools if it is even possible.

The thread in question is here:

http://www.cloudynights.com/ubbthreads/ ... art/3/vc/1

and the data is available from this link.
http://sdrv.ms/154NAcz


Thanks!
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admin
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Re: Achieving Color in Galaxies

Post by admin »

midwayexpress wrote:I have been evaluating image processing software to go with my new setup. Recently I discovered that I was still having problems with DSS due to the file save bug. I finally resolved the problem and learned through the help of the folks at cloudynights how to achieve color in my galaxy shots with photoshop. Now I would like to learn how to achieve the same effect with Startools if it is even possible.

The thread in question is here:

http://www.cloudynights.com/ubbthreads/ ... art/3/vc/1

and the data is available from this link.
http://sdrv.ms/154NAcz


Thanks!
Hi,

StarTools can certainly help you here, but I noticed some severe banding (vertical columns) in your data. Have you observed this yourself?
Did you use bias or dark frames?
The data, as-is, makes automated background color calibration with the Wipe module rather hard (as it keeps varying all over the place).
The only workaround here is to not bring out as much detail (which seems to be what the folks using PhotoShop have been doing). What you can do then is use the color module and change the Saturation and R, G and B values (which in turns changes the color in CIELab space). Better calibrated data would help a lot to tease out a good bit more detail from your subs. I can certainly see (and prove) you've captured it, but the detail, along with the color information is somewhat mangled by the banding.
I can show you what to do in StarTools to get somewhat correct color nonetheless if you want, but it would be a better (and more reproducible!) idea to calibrate data better so that the 'standard' way of doing things can be used!

Cheers,
Ivo Jager
StarTools creator and astronomy enthusiast
midwayexpress
Posts: 69
Joined: Sat Jan 12, 2013 9:42 pm

Re: Achieving Color in Galaxies

Post by midwayexpress »

You are correct. I'm not sure why I have so much vertical banding as this is the first time I have had that problem. I used 30 darks of equal exposure time to the lights shot at the same time on each night. I generally don't use bias frames.
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Re: Achieving Color in Galaxies

Post by admin »

midwayexpress wrote:You are correct. I'm not sure why I have so much vertical banding as this is the first time I have had that problem. I used 30 darks of equal exposure time to the lights shot at the same time on each night. I generally don't use bias frames.
Hmmm... strange! It could be something just went awry during the stacking?
The arms are clearly there and I was able to tease out some further structures nearer to the core as well - I hope we can slavage this one for all it's worth!
Ivo Jager
StarTools creator and astronomy enthusiast
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