Chapter 22. Designing Graphics with the Web Palette
The web palette
is a set of 216 colors that will not dither on Macs or PCs and is
built into all the major browsers (it is discussed in more detail in
Chapter 3, "Web Design Principles for Print Designers"). When a browser is running on a
computer with an 8-bit monitor (capable of displaying only 256 colors
at a time), the browser refers to its internal web palette to make up
the colors on the page.
If the browser is running on a 24-bit display, the web palette does
not come into effect and all colors are displayed accurately. See
the sidebar "When Not to Worry About the Web Palette" for
other instances when the web palette does not apply.
Most often, remapping images to the web palette in the browser
results in undesirable dithering. Not only that, sometimes flat
colors shift to the nearest web-safe colors without dithering. The
algorithm for deciding which colors to shift and which to dither (as
well as choosing where to shift) differs
depending on the browser brand and version.
All of this shifting and dithering means unpredictable image quality
on 8-bit monitors. But there is one thing that is
predictable -- the web palette. If you use colors from the web
palette in the image in the first place, you have the advantage of
controlling how the image appears on 8-bit monitors. It requires a
little extra effort and an adjustment to a limited color choice, but
the payoff is that you, not the browser, control whether and how the
There are two opportunities to apply the web palette in the image
creation process. The first is to choose web-safe colors when you
design the image (particularly for areas of flat color). The web
palette can also be applied to the image when reducing it to Indexed
This chapter looks at both approaches to using the web palette in
graphics. The techniques apply to graphics that use 8-bit palettes
such as GIF or PNG. Because PNG is not widely supported at this time,
GIF is featured in the following examples.
When Not to Worry About the Web Palette
There are some instances when you don't need to be concerned
with the web palette:
- If you don't care about performance on 8-bit monitors
The web palette only comes into play on 8-bit monitors; 16- and
24-bit monitors can accurately display just about any image. As of
this writing, only about 5-7% of web users have 8-bit displays.
However, in the interest of keeping the lowest common denominator in
mind, web designers continue to use web palette colors in their GIFs.
You may find that your clients still insist upon it to maintain
- If your image is primarily photographic
First, if you're starting with a purely photographic image, you
should save it in JPEG format. But let's say you have a good
reason for saving it as a GIF. Because the image is going to dither
anyway when you reduce its colors, and because dithering can be
beneficial in photographs, you do not need to apply the web palette.
Selecting an adaptive palette (a customized palette based on the
colors most used in the image) is a better choice during the
conversion process for maintaining the quality of the image.
- If your image is in the JPEG format
The web palette is irrelevant for JPEG images because they are
24-bit, nonpaletted images by definition. In addition, even if you
have flat areas of web-safe colors in your original image, they will
get shifted and distorted during the JPEG compression process.
22.1. Designing with Web-Safe Colors
If you are creating graphics from
scratch, especially graphics such as logos or simple illustrations
that contain areas of flat color, you can use web palette colors
right from the start. In this way, you can be certain that your
graphics will look the same for all users. Figure 22-1 shows how dithering could have been avoided if
the image had used colors from the web-safe palette. Remember,
it's the flat color areas where using web-safe colors makes the
Figure 22-1. Designing with web-safe colors prevents dithering
The major drawback is that with only 216 colors to choose from (a
good 30 of which you'd never be caught dead using for
anything), the selection is extremely limited. (See Section 22.4, "Color Blenders" in this chapter for one
approach to overcoming the limited choice of colors.)
The trick is to have the web palette colors available in a Swatches
palette or in whatever device your graphics program uses for making
colors handy. You should be aware, however, that even if you select
web colors for fills, any shades of colors created by soft drop
shadows or anti-aliased edges between areas of color will probably
not be web-safe.
Web Palette on 16-Bit Displays
16-bit (also called "high color") displays must
mathematically approximate colors from the true color space, slight
color shifting and dithering occurs even if you choose colors from
the "safe" web palette. Unfortunately, over half of web
users today use 16-bit monitors, which means that your colors
aren't looking the way you think over half the time.
This is most noticeable for pages with graphics that are intended to
blend seamlessly with a tiled background graphic or specified
background color. Although the foreground and background elements may
have identical web-safe RGB values, on 16-bit displays, colors shift
and dither in a way that causes the "seams" to be
Which elements shift and which get dithered seems to depend on the
browser and operating system combination, so it's difficult to
anticipate. If the mismatched colors concern you, making the edges of
your graphics transparent instead of a matching color may help
eliminate the dithered rectangles on 16-bit displays.
Webmonkey (an online developers' magazine) has an article
called "Death of the Websafe Color Palette?" by David
Lehn and Hadley Stern that does a great job of explaining how
web-safe colors fail in the 16-bit environment. It includes a
thorough technical explanation of how 16-bit color works as well as
results of their web palette testing. It is available at http://hotwired.lycos.com/webmonkey/00/37/index2a.html.
22.1.1. Tools with Built-in Web Palettes
Not surprisingly, with the explosion of the Web's popularity,
the web palette is finding its way into many commercial graphics
tools. The web palette is known by many names, including Netscape
Palette, Web 216, Browser-safe Palette, Non-Dithering Palette, the 6
6 × 6 Cube, and so on -- but you should recognize it
when you see it.
- Adobe Photoshop 5+
Version 5 and up ships with the Web Safe Colors CLUT file (see the
following section) in its Color Palettes directory. These can be
easily loaded into the Swatches palette by selecting Replace Swatches
or Load Swatches from the Swatches pop-up menu.
- Adobe ImageReady (bundled with Photoshop 5.5 and higher)
ImageReady was created specifically for the optimization of web
graphics, so the web palette comes preloaded in the Swatches palette.
- Macromedia Fireworks
Fireworks also has the web palette available in its Swatches palette
by default. In fact, it is difficult to use non-web-safe colors in
Adobe Illustrator 7.0 and higher
Version 7.0 of Adobe Illustrator introduced the ability to work
within the RGB color space (instead of being limited to CMYK as in
previous versions), so you can color your graphics and even export
them directly to GIF format. To select colors from the 216 web-safe
colors, select Windows Swatch Libraries Web.
- Macromedia Freehand 7.0 and higher
You can select colors from the Websafe Color Library, under Options
on the Color Palette. Colors appear with their decimal and
hexadecimal RGB values.
- Macromedia Director 5.0 and higher
You can find the web palette under the Xtras pull-down menu. Look for
the palette called "Netscape."
- Macintosh System OS8
MacOS8 comes with an HTML Color Picker in addition to the
standard Color Picker. This tool makes selecting web-safe colors
extremely easy via slider bars that snap into place at the safe color
values. It also translates the colors into the hexadecimal values
that HTML and browsers understand. (See Chapter 15, "Forms"
for more information on hexadecimal numbering.)
- Pantone ColorWeb Pro
ColorWeb Pro is a Mac-only product that enables designers to select
web-safe colors via an addition to the Macintosh Color Picker. It
also has printed swatch books that provide Pantone color equivalents
for the web palette when you need to coordinate your web page with a
printed piece. Another swatch book lists traditional Pantone ink
colors, but lists their digital equivalents in decimal and
hexadecimal RGB values.
22.1.2. Color Look-Up Tables (CLUT Files)
Photoshop and some other
graphics tools save palettes in files called CLUTs (Color Look-Up
Table). To make the web palette available in the Swatches palette,
you need to load the appropriate web CLUT file using Load Swatches,
Replace Swatches, or some equivalent command.
22.214.171.124. Creating a CLUT file in Photoshop 4.0
Photoshop 5.0 ships with the Web Safe
Colors CLUT file in its Color Palettes folder, but Photoshop 4.0 does
not. If you are using Version 4.0, it's easy enough to create
one as follows:
Convert any RGB image to Indexed Color.
In the Indexed Color dialog, select Web from the Palette pop-up menu.
Select Image Mode Color Table. Although the Table
pop-up lists Custom as the current option, the table itself contains
the 216 browser-safe RGB values.
Click the Save button, and save the color palette. Name it
descriptively and save it into Photoshop's Color Palettes
Load these colors into the Swatches Palette by choosing Replace
Swatches from the Swatches Palette submenu.
Now you can select from swatches of web-safe colors to fill areas of
your graphic. If you don't want to create the CLUT file
yourself, you can download it from Lynda Weinman's FTP site, as
explained in the following section.
126.96.36.199. CLUT files for other graphics programs
Many commercial tools that don't ship the web palette in their
color selector tools (including Photoshop) allow you to load in
palette files. Lynda Weinman, author of a well-known series of
books on web design, has created a collection of browser-safe palette
files that can be loaded into the following software packages:
Paint Shop Pro
clut (in Painter folder)
All of these files can be downloaded from Lynda's site:
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