Re: [APML] LRGB and IC1805 Redo

["Volker Wendel" <volker@spiegelteam.de>]

Hi Rob,

the image is much better now, but still contains the salmon color in the
brightest areas, where the information of white from h-alpha and the red of
the nebula from the color information is higher than 255. As I told you
before, try the "Replace color" tool in PSP6.0 (image-adjust-then 9th tool
from top) and select the brightest areas which look a bit burned out and
change the saturation up to more color and lower the brightness a bit.

The problem due to LRGB with a red filtered luminance channel is that you
overweight the red stars and nebula parts. In this image there is no problem
with these nebula parts, they are all red, but the image looks reddish in an
overall look because many red stars come out more than others. But hey,
every processing has itīs own problem....

Volker
www.spiegelteam.de



----- Original Message -----
From: "Robert Gendler" <robgendler@worldnet.att.net>
To: <astro-photo@seds.org>
Sent: Thursday, October 11, 2001 2:23 AM
Subject: [APML] LRGB and IC1805 Redo


> I've reprocessed my IC 1805 according to the helpful comments
> made by Volker and Chuck and others.
> I think the color is better and the image isn't blocked up anymore.
> Any comments are appreciated. The image is at
> http://robgendler.astrodigitals.com/1805.html
> As far as LRGB technique I think people should be careful about
> condeming it based on one flawed image. The problems with my
> first image weren't due to LRGB or CCD or photoshop. It was my processing
> (sleep deprivation probably didn't help much <G>). Also IC1805 isn't a
> traditional LRGB. The luminance is a high contrast H-alpha image rather
than
> an ordinary greyscale image. H-alpha tends to wash out the color.
> Basically the contrast needed to be cut back a bit.
> You can see many LRGB images on my web site where the
> color is not washed out.
> To respond to Chucks inquiry about RGB's with CCD here are a few
> http://robgendler.astrodigitals.com/Trap.html
> http://robgendler.astrodigitals.com/6960.html
> http://robgendler.astrodigitals.com/VeilMos.html
> http://robgendler.astrodigitals.com/6559.html
> Its possible to do plain RGB with CCD's and amateur equipment
> but good results are obtained only with bright objects. Professional
> RGB images are made with large aperture scopes so adequate S/N can be
> obtained easily. With dim objects and small aperture scopes S/N is
severely
> compromised
> when filters are used and image quality suffers. LRGB is a technique that
> offers the amateur a chance to image dim objects in color using relatively
> small aperture
> instruments.
> Rob Gendler
> Email: robgendler@att.net
> Web site: http://robgendler.astrodigitals.com
>
>
>
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