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RE: [APML] ESO Tarantula CCD image
Jerry, Outstanding, now you have a new tool to bring those deep astroimages
to life!
Chris Schur
Astrophotography: http://www.psiaz.com/schur/astro/index.html
-----Original Message-----
From: owner-astro-photo@seds.org [mailto:owner-astro-photo@seds.org]On
Behalf Of Jerry Lodriguss
Sent: Saturday, June 15, 2002 3:08 AM
To: astro-photo@seds.org
Subject: RE: [APML] ESO Tarantula CCD image
Hi Chris, Sean,
I stand corrected. You are very right!
I can't say I have a clue as to why this works, but I did a bunch of
experiments last night and the numbers back yall up.
I did find out a couple of interesting things. Just converting the color
image to grayscale gives a better signal to noise ratio than averaging the
individual color channels into a new luminance image.
At least, the way I averaged them, it did. But, maybe I didn't average them
the right way.
Anyway, I have all of the results of my experiments at:
http://www.astropix.com/HTML/TEST/TEST1.HTM
It's pretty graphics heavy, so it may take a while to load for those with
slow connections.
I also have the original color image available for download from that page
as an uncompressed TIFF if anyone would like to verify my findings, or try
new experiments.
I learned something new last night, and it was fun. So, thanks Chris and
Sean!
Jerry
At 02:25 PM 6/14/2002 -0700, you wrote:
>Jerry, my understanding on how this works is that in an image, the grain is
>essentially a luminance noise, and much less color data noise. If I add
the
>R+G+B and say thats my new luminance, it will of course have much less
noise
>than any single frame. That appears to be the secret, a standard RGB
>combines the three channels in such a way that the noise is "colored" and
>much more visible. Some people even blur the RGB and combine with a R+G+B
>luminance to make an even smoother but equally sharp image. This is the
>best I can explain it. I have used it dozens of times, and done carful
>comparisons. It works. You might try splitting an RGB 16 bit image in PS,
>and make a Lab this way to compare.
Astronomical photography: http://www.astropix.com
Sports Photography: http://www.astropix.com/SPORTSPIX/INDEX.HTM
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