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Following are the most commonly used
graphics
file
formats for putting graphics
on the World
Wide Web and how each differs from the
others.
JPEG/JPG
-
Short for Joint Photographic Experts Group, the
original name of the committee that wrote the
standard. JPG
is one of the image file formats supported on the
Web. JPG
is a lossy compression technique that is designed to
compress color and grayscale continuous-tone images.
The information that is discarded in the compression
is information that the human eye cannot detect. JPG
images support 16 million colors and are best suited
for photographs and complex graphics.
The user typically has to compromise on either the
quality of the image or the size of the file. JPG
does not work well on line drawings, lettering or
simple graphics
because there is not a lot of the image that can be
thrown out in the lossy process, so the image loses
clarity and sharpness.
GIF
-
Short for Graphics
Interchange Format, another of the graphics
formats supported by the Web.
Unlike JPG, the GIF
format is a lossless compression technique and it
supports only 256 colors. GIF
is better than JPG for images with only a few
distinct colors, such as line drawings, black and
white images and small text that is only a few
pixels high. With an animation editor, GIF
images can be put together for animated images. GIF
also supports transparency, where the background
color can be set to transparent in order to let the
color on the underlying Web page to show through.
The compression algorithm used in the GIF
format is owned by Unisys, and companies that use
the algorithm are supposed to license the use from
Unisys.
PNG
-
Short for Portable
Network Graphics, the third graphics
standard supported by the Web
(though not supported by all browsers).
PNG
was developed as a patent-free answer to the GIF
format but is also an improvement on the GIF
technique. An image in a lossless PNG
file
can be 5%-25% more compressed than a GIF
file of the same image. PNG
builds on the idea of transparency in GIF
images and allows the control of the degree of
transparency, known as opacity. Saving, restoring
and re-saving a PNG
image will not degrade its quality. PNG
does not support animation like GIF
does. |