Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: Rocket Pooch on Oct 30, 2010, 18:58:39

Title: Star subtraction
Post by: Rocket Pooch on Oct 30, 2010, 18:58:39
Hi,

I remeber Fay saying something about this and how to do it, here's a link.

Chris

http://darkhorizons.emissionline.com/stars.htm
Title: Re: Star subtraction
Post by: Carole on Oct 30, 2010, 20:15:20
That's pretty nifty.  Will be useful.  I knew how to remove the stars but not how to fill up the holes.

Carole
Title: Re: Star subtraction
Post by: The Thing on Oct 30, 2010, 21:19:27
Deep Sky Stacker will create a star mask image for all the stars it has identified if told to. This can be used in GIMP/Photoshop to mask of the stars, create selections etc. Shame I've never got round to using it...
Title: Re: Star subtraction
Post by: mickw on Oct 30, 2010, 22:37:39
If for example this technique was used on something like M45 to enhance the nebulosity without bloating the stars, would the new "star layer" need to be applied behind the tweaked nebulosity layer ?

I'm thinking that the other way round would create dark haloes ?
Title: Re: Star subtraction
Post by: Rocket Pooch on Oct 30, 2010, 22:41:18
Just had a play and if you put the nebula layer in front of the stars as a luminance it works really well.

Title: Re: Star subtraction
Post by: Rocket Pooch on Oct 30, 2010, 22:43:36
Before
(http://farm5.static.flickr.com/4103/4987083630_6ea38b75d3_z.jpg) (http://www.flickr.com/photos/13007140@N05/4987083630/)
ic59-63-HaGB-Big (http://www.flickr.com/photos/13007140@N05/4987083630/) by chrissuddell (http://www.flickr.com/people/13007140@N05/), on Flickr

After, bit not processed properly
(http://farm2.static.flickr.com/1067/5129770200_42b867279b_z.jpg) (http://www.flickr.com/photos/13007140@N05/5129770200/)
ic63test (http://www.flickr.com/photos/13007140@N05/5129770200/) by chrissuddell (http://www.flickr.com/people/13007140@N05/), on Flickr
Title: Re: Star subtraction
Post by: mickw on Oct 30, 2010, 22:52:57
Thanks for that Chris
Title: Re: Star subtraction
Post by: MarkS on Oct 31, 2010, 07:38:32

Very interesting Chris. 
It certainly enhances the nebulosity in your image. 
I might experiment with the technique.

Mark