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Re: color orange

From: Leonard R. Kasday <kasday@acm.org>
Date: Wed, 25 Aug 1999 11:05:04 -0400
Message-Id: <3.0.32.19990825110457.00e0d658@pop3.concentric.net>
To: "jonathan chetwynd" <jay@peepo.com>, "jonathan chetwynd" <jay@peepo.com>, "Kynn Bartlett" <kynn-hwg@idyllmtn.com>
Cc: <w3c-wai-ig@w3.org>
Hi Jonathan,

Interesting question about why orange is dull on PC Monitors.  The answer
lies in physics and visual perception.  I'll get to that in a moment.

First let me see if I understand the relation to accessibilty.  You're
concerned with designing web sites for non-readers, so you want to pack in
as much meaning as possible without words.  Since color is a way to convey
meaning you want as large a gamut as possible.  So limits on Orange are a
problem.  Is that your concern?

It occurs to me that there are other accessibility concerns too regarding
color.  Since color carries meaning... at least subjective meaning (joyous,
sad, exciting, etc) I would guess that some blind folks would want to know
about the color scheme, in at least some situations.  That brings up the
question, when you're describing the color scheme, whether to name the
colors, or describe the mood you're trying to convey (e.g. "joyous", "sad",
"exciting" etc.) or both.  Another accessessibility issue in the larger
sense is that the meaning of a color is context and culture specific. Plus,
of course, there's the legibility of colored text against colored
backgrounds, like what they're looking at at University of Toronto.

Anyway, here's why orange is so dim.  PC monitors combine red, green, and
blue light to make white.  To get any color, such as orange, you actually
dim one or more of red, green, or blue.  For orange, in particular, you
turn off blue and dim green quite a bit.  (You can make it brighter by
adding blue, but then it also gets paler.)  So orange is a lot less bright
than the full brighness white.  It's also less bright than other colors.
For example, it's dimmer than yellow which doesn't require you to dim green
so much.

(Note to people who are used to mixing paints: what I'm saying  sounds all
wrong to you because rules for mixing paints are different than rules for
mixing lights.  Technically, it's subtractive color mixture vs. additive
color mixture).

Your eye (actually your eye and brain) judges brightness by comparing it
with the surroundings.  So if you you have orange in the context of other,
brighter colors it looks dim by comparison.  Or if the whole background is
orange, it's dim in relation to the room surroundings.  Like I say you can
add blue to make it brighter, but then it gets paler.

So if you want to make the orange brigher make the area small and surround
it with dark colors.  Samples of color combinations are at

http://astro.temple.edu/~kasday/color/colortable.html

In particular, you can see orange and other colors against different
backgrounds in fig. 2.  Note that orange looks different depending on
whether is the big area or a text against a big area; and what the
background is.

By artistic standards, what I've said is pretty simple.  There are more
complex techniques that artists use when they are painting highlights,
reflections, and lights.  You can find descriptions in books on  advanced
oil painting techniques, for example.  For example, you can make a surface
look brigher by surrounding it with a dark color and then smoothly shading
that surround to light again.  A good way to make a moon glow.

Just remember though that the way you get colors on a PC are different than
how you get them mixing paints so you'll have to ignore what the books says
about mixing colors.  Just look at the final colors they wind up with.

Len

At 08:18 AM 8/24/99 +0100, jonathan chetwynd wrote:
>Perhaps you remeber the days when snooker was in black and white on
>television?
>
>It was not very satisfactory, nor accessible.
>
>without a commentary, almost useless.
>
>So perhaps you could answer my question as to whether your screen has a
>vigorous and acid orange.
>
>Answers from any and all members would be appreciated.
>Color is a complex problem, words, perhaps not the best examplars.
>
>Perhaps someone out there can make my oranges sing.
>
>
>jay@peepo.com
>
>a www for those learning to read.
>
>Please send us links to your favourite websites.
>Our site www.peepo.com is a drive thru.
>When you see a link of interest, click on it.
>Move the mouse to slow down.
>It is a graphical aid to browsing the www.
>We value your comments.
>
>
>
>
>
-------
Leonard R. Kasday, Ph.D.
Universal Design Engineer, Institute on Disabilities/UAP, and
Adjunct Professor, Electrical Engineering
Temple University

Ritter Hall Annex, Room 423, Philadelphia, PA 19122
kasday@acm.org        
(215) 204-2247 (voice)
(800) 750-7428 (TTY)
Received on Wednesday, 25 August 1999 11:02:16 UTC

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