RE: Luminosity channel...
RE: Luminosity channel...
- Subject: RE: Luminosity channel...
- From: email@hidden (Bruce Fraser)
- Date: Mon, 24 Sep 2001 09:50:05 -0700
At 1:51 PM -0230 9/24/01, shAf wrote:
Bruce writes ...
At 9:53 AM -0400 9/24/01, CS Carl Stawicki (4211) wrote:
>Hey kids-
>
>Does anyone know how PhotoShop calculates the luminosity channel? ...
>
It's the L* (Lightness in Photoshop terminology) channel that you'd
get if you converted the image from whatever space it's in to Lab.
The "math" I wanted to remember and reply with was something akin to the
percentages used if creating a grayscale with the channel mixer. Isn't it
something like R=30, G=50, B=20(???)
Actualy, I've just gone and checked, and while I'm reasonably sure
that what I said (Luminosity histogram=L channel) was true in
previous versions of Photoshop, it isn't in 6.0.1. It's also not the
histogram of what you'd get if you converted to grayscale. I guess I
don't know...
Bruce
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