From: Colin Rafferty <colin@xemacs.org>
Subject: Re: HTML foreground and background colors being the same... poll time!
Date: 03 Dec 1998 09:54:32 -0500 [thread overview]
Message-ID: <vgvyaop6ztj.fsf@ms.com> (raw)
In-Reply-To: "William M. Perry"'s message of "Thu, 3 Dec 1998 09:00:21 -0500"
William M Perry writes:
> I'd vote for (c), but I have no clue on how to go about finding or writing
> a good contrast-finding algorithm. Anyone out there know of one?
I vote for (c), but I know that finding contrasting colors is hard to
do. However, since all you need is a single constrasting color, you
could choose between black and white.
;; Take the "average" level, and go opposite
(defun infer-contrasting-color (r g b)
(if (and (<= r 255)
(<= g 255)
(<= b 255))
(if (< (+ r g b) 384) "white" "black") ; (/ (* 256 3) 2) => 384
(if (< (+ r g b) 98304) "white" "black"))) ; (/ (* 65536 3) 2) => => 382
;; Colin
next prev parent reply other threads:[~1998-12-03 14:54 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-12-03 14:00 William M. Perry
1998-12-03 14:26 ` Hrvoje Niksic
1998-12-03 14:37 ` Didier Verna
1998-12-03 14:44 ` Hrvoje Niksic
1998-12-03 14:54 ` Colin Rafferty [this message]
1998-12-03 16:08 ` Ken McGlothlen
1998-12-03 14:56 ` Bill White
1998-12-03 16:43 ` Wes Hardaker
1998-12-03 18:49 ` Matt Armstrong
1998-12-09 16:06 ` William M. Perry
1998-12-04 1:19 ` Laurent Martelli
1998-12-04 5:31 ` Felix Lee
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