Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!rutgers!ames!ucbcad!ucbvax!sdcsvax!hutch
From: hutch@sdcsvax.UCSD.EDU (Jim Hutchison)
Newsgroups: comp.sys.amiga
Subject: Luminance correction values: b&w printers
Message-ID: <2426@sdcsvax.UCSD.EDU>
Date: Wed, 7-Jan-87 10:53:48 EST
Article-I.D.: sdcsvax.2426
Posted: Wed Jan  7 10:53:48 1987
Date-Received: Wed, 7-Jan-87 22:51:23 EST
Reply-To: hutch@sdcsvax.UCSD.EDU (Jim Hutchison)
Organization: UCSD EMU Project (Educational Microcomputer Unix)
Lines: 21
Keywords: correctness

<>
I have an open question for the person(s) who wrote the routines in the
printer device which convert color to black and white for black and white
printers.

Did you apply the correction values?  I usually forget and kick myself later,
but then add them as they make a real difference.

What am I talking about?  The human eye is more sensitive to luminance in green
than red than blue.  Thus using equal weighting for luminance of these colors,
will produce a different image (as if the colors had been increased).

light = 0.30 * red + 0.59 * green + 0.11 * blue

A quick perusal through Foley & Van Dam will lead to further enlightenment,
which they phrase can better than I could.
-
-- 
    Jim Hutchison   		UUCP:	{dcdwest,ucbvax}!sdcsvax!hutch
		    		ARPA:	Hutch@sdcsvax.ucsd.edu
Madness, where would we be without it?  sane.  DES drugs cia ussr raygun laser