Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!bcm!etaylor
From: etaylor@wilkins.iaims.bcm.tmc.edu (Eric Taylor)
Newsgroups: comp.windows.x
Subject: Color to Gray Scale
Message-ID: <3206@gazette.bcm.tmc.edu>
Date: 14 Dec 90 19:20:48 GMT
Sender: usenet@bcm.tmc.edu
Reply-To: etaylor@wilkins.iaims.bcm.tmc.edu (Eric Taylor)
Organization: Baylor College of Medicine, Houston, Tx
Lines: 18
Nntp-Posting-Host: wilkins.iaims.bcm.tmc.edu


Here is a question that has always bothered me:

Why is the formula for a gray level =
	.3 * red + .6 * green + .1 * blue   (approximately)

It seems to me that you REALLY want :

	sqrt((red * red + green * green + blue * blue) / 3)

since gray is a measure of intensity.


--
					Eric Taylor
					Baylor College of Medicine
					etaylor@wilkins.bcm.tmc.edu
					(713) 798-3776