216 Web Safe Colors
•Macintosh Computers and
Window computers have different
color indexes of 256 colors
•Web safe: only 216 colors that
match perfectly on the monitor
when seen on both platforms
• Thus, for reliable graphic
design, use only web safe colors
•Graphics files take up a lot of memory
•Causes sluggish performance on web sites
•Two types of graphic compression formats
have been become standard for web use.
Joint Photographic Experts
Group-A compression standard
developed for still images.
JPEG compression is
recommended for photographic
-style images and continuous
-tone images (e.g. used for
Graphics Interchange Format
A graphic compression format
developed by CompuServe to
allow graphics to load quickly on
easily through a network.
Best used with flat graphics and
such as logos and drawings.
GIF vs. JPEG
JPEG=15,343 bytes GIF=26,979
Gif vs JPEG
JPEG=42,268 bytes GIF=21,507 bytes
Gif files will allow you to set one color to
be transparent. This means it will allow
the web pages background to be
viewed through this color.
Placing transparent objects on background colors that match the
transparency color will prevent haloing seen in the previous slide.
Interlacing allows the picture
to gradually fill in by adding
lines top to bottom and repeats
this till the image is complete.
Standard format fills from top
Interlacing allows the viewer to see a preview of the
entire image before it finishes downloading .
The image on the UMD Psychology dept. web site at
interlaced. Notice how it loads…
Anti-Aliasing smoothes the edges of a
DPI - Screen Resolution
•Monitors read 72 dots per inch in resolution
• Thus there are about 5,200 dots per square inch.
•Printed documents usually use 150 dpi or higher
with 1, 440, 000 dots per square inch.
•For web photos, set your image resolution to 72
•Sony Mavicas are set to take 72 dpi photos
•72 pixels to an inch.
•Pixels are the standard measuring tool for computer
•Web page designers design with for a monitor view
of 640 pixels wide and 480 pixels in height as a
•This allows for the lowest common denominator in
monitors to view the entire screen. This will change
with advances in technology.
Hexadecimal Color Codes
Web colors are coded in six
digit code combining numbers
and letters. You can find the
codes for web safe colors on
web sites for graphics editors
or it will be built into
sophisticated web graphic
editing programs like
Draw a graphic from
Scan a picture with a
Draw using graphic
or PowerPoint draw
Copying from the Web
Free Web Art Site
Purchasing Image CD’s
Eyewire product index
Creating World Wide Web Graphics
Making Web Graphics
Creating Graphics for the Web