Small Background Galaxies in a Starmask

[iksose7]

Hi,

I have a image of Abell 1656 that i have just started working on. I am having difficulty when building a star mask to stop small background galaxies being included in the mask. Normally if this happened in an image i would just clone stamp the mask to remove where the galaxies have been included. That is fine if there are just a few included galaxies but this image contains many as you can imagine with it being a galaxy cluster, hundreds.

Is there anyway to stop them being included as stars? it would be handy if a algorithm was included that rejected anything shaped like a galaxy but i dont see that being possible?

Thanks

[RickS]

Have you tried building the star mask on linear data with only a small Midtones stretch?  The true stars will generally be brighter.  This won't get you all the smallest stars, unfortunately, but it might be good enough to mask all the big ones without including the galaxies.

Cheers,
Rick.

[iksose7]

Just tried that Rick and it is avoiding a lot of the stars and still picking up on some galaxies unfortunetely.

I may have found a slightly time consuming way to sort the problem. If i apply my luminance mask over my star mask, i can see which white spots on the star mask are galaxies. I can then just go around and clone stamp where galaxies have been included.

It may take a little while but will be worth it to get a good mask that only includes stars. Cant think of any other way.

Thanks for the suggestion though Rick, i appreciate it. Any others are welcome.

[oldwexi]

Hi iksose7!
I have provided a "Script" tool for creating finer StarMasks with the help of PixelMath.
It is included in the Blend Script as a selection in the "Overlay Mode" selection (StarMask)
Depending on the  "Starmask Thre:" ruler you get more or less fine stars in the mask.
IMG1 and IMG2 have to be the same.
Each time you move the ruler to a new value a new starmask is automatically created.
At the end (after Ready) you select the finest starmaks you think for use and throw away the rest .
Link to PI ForumPage with announcement and link to the script:
http://pixinsight.com/forum/index.php?topic=7846.msg51967#msg51967
 
Gerald