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The two main graphics
formats that Web browsers can read are GIF and JPEG. Each
is suitable for different types of images, so it's important
to know which one to choose.
GIF is a
graphic format using a compression designed by CompuServe.
They have the extension ".gif" and are best used
for illustration, line art and simple graphics that have
little or no shading.
They support up to 256 colors and use a lossless compression
which allows for all detail to be maintained during the
compression process. Most clip-art and text-based images on
the Web are
of the GIF format.
JPEG is a graphic format
designed by Joint Photographic Experts Group (JPEG). They have
the extension
".jpg" and
are best used
for photographic images. JPEG files can support up to
16 million colors as compared to GIF's 256 colors. It uses
a lossy compression
which means certain parts of images are permanently thrown
away so that the files take up less storage space. Most
photographic images on the Web are of the JPEG format.
Make smaller images.
If you must use large graphics,
use
small, clickable thumbnails to link to the larger version.
Compress
your images by choosing the right format for your graphics.
A good rule of thumb is to use GIF for
illustration
and line art images and use JPEG for photographic images.
Reduce colors in your
images. The fewer colors you include in your image, the less
information the image
needs to
keep track of; as a result, the smaller the file
size becomes. For example, anti-aliasing, a technique that
uses intermediate
colors to blend edges in images, will increase your
image size
by 30 percent or more. |
