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M31 processing issues


Daddystu
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M31. 90x60 second subs and 10x300 second subs stacked together with associated darks using groups in DSS. 20 bias frames in main group but no flats used. I have tried to process this in a number of different ways using CS5, paint.NET and GIMP. The problem i'm having is keeping the inner detail when enhancing the outer spiral arm detail. This image is my best compromise between the two thus far. The blue channel has been increased slightly relative to the others as the red channel was giving me noise that was difficult to process out. Comments/criticisms/re-processing attempts most welcome. post-28858-0-58145700-1377117924_thumb.p

Edited by Daddystu
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Hi!

Red targets such as nebulae have a tendency to make a whole image red, and blue galaxies do the same but obviously blue instead. It's pushin the colour we expect to see too much across the board that causes this. (Yes I still fall in that trap myself...)

So, your image leans towards blue here. In PS you have many tools at hand. GradientXterminator for instance is well worth the cash, and it can bring back a background that's gone astray. Layers and masks allow you to stretch or process different sections of an image differently. M31 may well be suited for a separate layer for the central region around the core.

There are plenty tutorials here on SGL how to work with layers etc and they're worth reading through. In a recent thread MartinB went through masks as well and this can be a very useful weapon in your image above.

But, you're really not far off the mark in your edit. I think the galaxy looks very nice, there's is still star colour that you can boost further. You can also play with saturation - the sponge tool, and you can lasso off the galaxy and sharpen it with a duplicate layer that you apply a high pass filter on and merge back as 'soft light'. (A method I was given the heads up on very recently here by a fellow member.)

M31 is quite a difficult target. It's really quite faint compared to many more distant galaxies. You're on the verge of a really fine image I think!

/Jesper

Edited by Jessun
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Thanks for your input Jesper. I have had a fiddle with the techniques you mentioned and I shall be processing the core region separately to the outer arms. That re-process of yours looks miles better and although the outer arms are still a little faint it does show that there is a good level of detail in my data. Many thanks.

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It was just to show that you can do simple work on the background and lift the arms a bit. It's hard to 'reverse process'.

Many M31 images are 10 hour+ kinda jobs, so keep collecting subs on this one. It looks very promising.

/Jesper

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M31. 90x60 second subs and 10x300 second subs stacked together with associated darks using groups in DSS. 20 bias frames in main group but no flats used. I have tried to process this in a number of different ways using CS5, paint.NET and GIMP. The problem i'm having is keeping the inner detail when enhancing the outer spiral arm detail. This image is my best compromise between the two thus far. The blue channel has been increased slightly relative to the others as the red channel was giving me noise that was difficult to process out. Comments/criticisms/re-processing attempts most welcome. post-28858-0-58145700-1377117924_thumb.p

Hi,

Just a basic work out in StarToolsas it really does not playing with already processed images, hope that you approve.

Regards,

A.G

post-28808-0-19976200-1377127268_thumb.p

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