Although the RGB color system uses 24 bits and therefore specifies
224 = 16,777,216 different colors, the cruel fact is that only
a small percentage of computers in the world (very expensive ones)
are equipped to display 24-bit
color. Many support only 8-bit color; these can display only
28 = 256 colors at any one time. Others support only 16-bit color.
In both cases, adjustments often need to be made. Different adjustments are
made by different systems and different browsers with different kinds of
techniques. It's VERY HARD to predict results for a wide variety of
So, what's a web designer to do? Today's lesson offers one possible
solution to this problem...
INDEX CARD #27:
COLOR PALETTES (27a)
What is a "palette"? Here's Webster's definition: a palette
(pronounced PAL-it) is the
range of colors used in a given painting or by a given artist.
What is a "system palette"? For system-level operations, computers
use a specific set of 256 colors, called the system palette.
MACs and PCs use slightly different sets, but there are 216 colors that are
shared by both system palettes.
What is the "web palette"? The web palette consists of the
216 colors that are shared by the MAC and PC system palettes. These 216
colors will render correctly on both MAC and PC displays. (However, these
colors may shift or dither on UNIX terminals.) The "web palette" is also
known as the Netscape Palette, Netscape 216,
Browser-Safe Palette, Web-Safe Palette, Non-dithering
Palette, and the 6×6×6 cube. (This last name
should make more sense momentarily.)
What is "color shifting"? Non-web-safe-colors specified in an HTML document
are usually replaced by the nearest available Web Palette color; this effect
is called color shifting. Do you see different colors below? If not,
then color shifting has taken place!
This is slateblue, #6A5ACD.
This is the nearest web-safe color to slateblue, #6666CC.
COLOR NUMBERS for the WEB PALETTE (27b)
Is it easy to recognize which colors are in the WEB PALETTE, from their
hexadecimal codes? YES! Each web palette color has a hexadecimal code
of the form RRGGBB, where RR, GG, and BB can only take on the following
00 or 33 or 66 or 99 or CC or FF
Thus, there are 6 choices for RR; there are 6 choices for GG; and there
are 6 choices for BB. Together, there are 6×6×6 = 216 web-safe
colors. This is why the web-safe colors are sometimes referred to as the
For example, #33FF00 is a web-safe color, but #33FF01 isn't.
What are the advantages to using only web-safe colors when designing
graphics and HTML pages? You'll know exactly what your page
will look like (color-wise, at least) to all your viewers. (Well... different
users may have set their preferences to use different link colors, or
different text colors ...)
(W27.2) Visit the "Paletteman" site again, and figure out if only web-safe colors
are being used:
Determine a color scheme for your homepage that you're pleased with. (You can
choose up to four colors, and a color for text.) In the next few lessons, you'll
learn how to set background and text colors and more.
(A27.1) Please read pages 3033 (from "Color in Browsers (The Web Palette)"
up to "Web authoring tools") in the Weasel Book.
(A27.2) Go to Table 5-2 (Color Names with their Numeric Values) in the Weasel Book, on pages 7982.
MARK the colors that are in the Web Palette. (These are the colors for which
the hexadecimal code and the
nearest web-safe color are the same). There are only ten named colors
that are web-safe!