# Re: color definitions

Eric Gauthier (eric@h61-24.centre.edu)
Sat, 23 Sep 1995 15:11:45 -0400 (EDT)

```From: Eric Gauthier <eric@h61-24.centre.edu>
Message-Id: <199509231911.PAA00931@gauthier.centre.edu>
Subject: RE: color definitions
To: www-html@w3.org
Date: Sat, 23 Sep 1995 15:11:45 -0400 (EDT)

Well,
the first thing to say is that the html hex colors
are listed in <RGB>.  The trick to it is that the numbers
listed are hexadecimal.  The red,green and blue components
are listed on a scale of intensity ranging from zero
to 255.  A quick lesson on HEX: 00 = the number zero.
09 = the number 9  0a = the number 10.  ff = the number 255.
Basically instead of having 9 digits you have 16 digits.
Anyways, I'm sure you can find a book on hex numbers.
So, the first two digits are the value for the red,
the next are for the green and the last set is for the
blue.  The <CMY> color scheme is almost the same
as <RGB>.  In this numbering scheme:
C = 255 - R   M = 255 - G    Y = 255 - B
R = 255 - C   G = 255 - M    B = 255 - Y
The <HSV> (also called the <HSB>) model is really different
from these two.  A good standard text to look in is:
Computer Graphics by Foley, van Dam, Feiner, and Hughes
(by Addison-Wesley Pub. Co). The second edition chapter
13.3.4.  The <HSV> model is complicated.  If you'd like
to know more detail about it and cannot find the book
mail me at: eric@gauthier.centre.edu

Eric Gauthier
```