From: gregharp_at_antispamdomain.not
Date: Wed Nov 26 2003 - 04:47:06 EST
Steve, Raoul, Dennis, Tony, et al,
Thanks for the pointers. I am definitely seeing some improvement doing
things similar to what you have suggested.
http://www.pbase.com/image/23638231
This image is made up of several layers (16-bit layers! Woohoo!). At the
bottom of the stack is the original image, of course. On top of that is a
copy with a feathered layer mask revealing just the nebulosity. Adjustment
layers (hue/saturation, levels, and color balance) are associated with that
layer to tweak the color and intensity.
Above that are two layers of just stars, selected from the original using
the magic wand and copied into their own layers. These both have levels
adjustment layers associated with them. In the case of the dimmer stars,
the levels are set so that they are mostly no longer there. This layer in
particular also has a layer mask applied that keeps it from affecting the
nebulosity.
I could probably play with this image for a long time.
In fact, I just did some more. :)
http://www.pbase.com/image/23638557
That image is the previous image with an additional layer of the nebulosity
that has been processed using the Median filter. The blending mode for this
layer was set to "Lighten" and it was placed above the normal nebulosity
layer. The result is a much smoother and even brighter nebulosity. I'm
probably getting a little close to "cartoonish" in terms of the look but I
am just sort of playing at this point.
Thanks to everyone.
Ok, that's my new personal best, at least until I work on it some more. :)
I also have some wide field shots of the belt and sword of Orion that I'm
still playing with.
Regarding Photoshop CS, there are several reasons I decided to go ahead and
upgrade:
1) RAW conversion for the 10D is now built in vs having to hack Camera RAW's
D60 filter. Also, there are quite a few more tweaks available in the
handling of RAW files including (interestingly enough) easy adjustments for
vignetting, etc. While I don't plan to use Adobe's RAW conversion for
astrophotography, I prefer it to anything else I have used for development
of RAW files for terrestrial photography.
2) Need I say it again: Layers (and may other features, including some of
the stock filters) now work with 16-bit images! I'm such a layers addict
(the above image has 10 layers) that I've been working strictly in 8-bit
mode once I get to Photoshop. While we all know that the output devices
we're using (be they monitors or printers) are limited to 8 bits per color
per pixel, as we all know from astro image processing it's still much better
to work in 16 bits for as much of the process as possible. This will be as
big a boon to my terrestrial photography as it will to my astrophotography.
3) CS has a live histogram that updates as you make changes. In my case,
this will mean I will begin using Curves more often, as a lack of feedback
in the form of a histogram has always been my main problem with them.
However, I haven't developed the habit yet.
4) There are quite a few new user interface features or improvements upon
old ones like the file browser, better automation/scripting, etc.
I like it...
--Greg
> -----Original Message-----
> From: sc02492 [mailto:sc02492_.at._yahoo.com]
> Sent: Wednesday, November 26, 2003 2:09 AM
> To: digital_astro_.at._yahoogroups.com
> Subject: [digital_astro] Re: How do I process this?
>
>
> Greg, nice shot of a difficult area. Here's a suggestion that you
> may already know about, but I'll mention it for others as well. The
> problem with these kind of shots is star bloating when you try to
> enhance faint areas using curves. It's sometimes possible to
> selectively enhance the nebula, without affecting the stars, by
> using a simple Photoshop technique:
>
> 1. Use the magic wand to select most stars.
> 2. Use the lasso tool on "minus" mode to remove any selected areas
> that inadvertently involve large sections of the objects of interest
> (the nebula in this case).
> 3. Use "Select", Expand (about 6 to 8 pixels), and then Feather
> (about 4-6 pixels). This will make a smooth transition between the
> stars and the background.
> 4. Here's the trick- go to select and choose "inverse". Now you
> have isolated only the nebula/sky areas, excluding the stars. You
> can make any adjustments you need (curves, selective color, filters
> like unsharp mask, etc.) without affecting the stars too much.
>
> Either way, I think you will benefit from a filter as well, as I
> think Raoul mentioned. Finally, could you let us know how much you
> like the new 16 bit Photoshop?
>
> Steve
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