Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!ames!sgi!shinobu!odin!cashew.asd.sgi.com!kurt
From: kurt@cashew.asd.sgi.com (Kurt Akeley)
Newsgroups: comp.sys.sgi
Subject: Re: Anti-aliased black lines?
Message-ID: <1991Mar1.175935.14612@odin.corp.sgi.com>
Date: 1 Mar 91 17:59:35 GMT
References: <9102281501.AA09895@cmcl2.NYU.EDU>
Sender: news@odin.corp.sgi.com (Net News)
Reply-To: kurt@cashew.asd.sgi.com (Kurt Akeley)
Organization: sgi
Lines: 9

I'm not an expert on the PI, but I understand that it uses only half of
the color indexes in the 16-index ramp when it generates antialiased
lines.  Probably the half that is used is either 0,2,4,6,8,10,12,14 or
1,3,5,7,9,11,13,15, but I don't know.  In any event, this would only
partially explain your observation.

-- kurt

p.s. I mailed this response to you some time ago, but the mail bounced.