StarTools

I am curious if there is a way to process the core and arms of a spiral galaxy separately when in the Colour Module. I just put five hours on Messier 77, and this finally allowed me to finally bring out the faint arms that surround the core.

The problem is that I used an Astronomik CLS CCD filter to cut through the local light pollution. My camera is a Canon 7D mkII full spectrum. It did a wonderful job. It allowed me to up my exposure time from 240 seconds to 420 seconds, and basically no hint of the bright background. I probably could go 10 minutes. Unfortunately this filter changes things to a more bluish tint, and seems to alter the end colour of the whole photo.

What I am looking for is to make the core a blue with red highlights, and the arms as a very faint blue. Unfortunately, the arms are coming out kind of a grayish brown, and I am guessing part of the problem is due to this filter I used. I'm actually trying to imitate some of the photos I have seen online. I know I am limited to how much I can manipulate this photo, especially since my OTA is only an ES102ED.

Does anyone know how I can work on the core and arms of a spiral galaxy separately. If it comes to layering, then I need directions to wherever there is a tutorial on how to do layering. I've not a clue as to how you can do layering with only one photo available.

Meanwhile I will keep working on this in the hope I discover something I am missing. I appreciate any suggestions you may have. Caley

Hi,

You're definitely right in that any issues/problems with the data should be handled during acquisition.
Filters will indeed change irrevocably and irreversibly change colours, though there are ways around that by also acquiring data in the visual spectrum without filters for the colors, while using whatever filter you see fit for the luminance.

While it is 'frowned upon' by some purists (including yours truly), you can definitely process different parts of the image if you really wish. All you have to do is put whatever part of the image you want to work on in a mask (use the Lassoo tool for example). Now the various modules (including the Color module) will only operate on that area, leaving the non-masked area alone.

If you have two versions of the image and wish to combine certain aspects/areas of them into a new image, you can indeed use the Layer module.

Simply load one image by conventional means, then, once in the Layer module, open the other image from within the Layer module. Now you can, again, use a mask to specify which parts of the 2 images you wish to use in the end result.