Re: [APML] Widefield Comet Machholz

Thanks Carlos! Thanks for the Wavelets tip. I'm really trying to understand and utilize this process.

Gary

----- Original Message -----

From: Carlos Milovic F.

To: Discussion of Film Astrophotography

Sent: Monday, January 31, 2005 1:12 AM

Subject: Re: [APML] Widefield Comet Machholz

Here's my first image processed entirely in PixInsight. I'm still having trouble getting the tail to come out good but I'll keep working on it. Anyone have a suggestion for doing this?

Hi Gary!

Very nice pic. Tha California nebula looks very good. It remainds me a lot a shot I made a year ago. Congrats.

The only think I guess that could help with the comet's tail is the use of wavelets. First, search the proper scale that isolates just the tail (if necessary, change the scaling function). Then, increase the bias of that layer to bring the tail more visible. Use this just as a test (with previews). For the final adjustement, you'll have to construct a ***very*** good mask, that prevents stars from saturation, and other artificial looks. Perhaps a inverted luminance can do that... in the wort case you'll have to play with PixelMath to combine several images to build the proper mask for your case.

Oh! Don't forget to use the "deringing" feature. This way you'll reduce the effect of dark haloes.

Another way to protect the stars would be to substract them first... use wavelets or SGBNR (without edges protections) to blur the image and then build a high-pass version.

Regards,

Carlos Milovic F.
-------------------------
Astro & Photo - CMF
http://www.astrophoto.vze.com
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