Re: [APML] Synthetic Luminance Channel for Film Images

[Jerry Lodriguss <jml@astropix.com>]

At 07:19 PM 6/15/2002 -0700, you wrote:
>One minor point here (or major point depending on your point
>of view):
>
>Converting an RGB to grayscale and then reapplying the result
>back to the L channel will cause a color shift.  I think this
>was discussed a while back here on APML.  This is because of
>how Photoshop converts to grayscale.
>
>So you are giving up color accuracy (whatever that means :-))
>to improve SNR.


Hi Shekar,

Man, I'm just trying to understand how a synthetic luminance could improve 
the s/n.

I haven't even thought about worrying whether the color is accurate when 
you do it.<G>

Mike Cook has passed on some comments from the SBIG list about this 
question of whether there is a real gain in s/n, and I am leaning back 
towards my original position, that there is no real gain.

I will post a more detailed explanation, but think about it... it's common 
sense. You don't get something for nothing.

Jerry

Astronomical photography: http://www.astropix.com

Sports Photography: http://www.astropix.com/SPORTSPIX/INDEX.HTM


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