GIF –
FREE TOPIC
The Graphics
Interchange Format, is a bitmap image format animation that
was developed by a team at the online services provider CompuServe led
by American computer scientist Steve Wilhite on June 15, 1987. It
has since come into widespread usage on the World Wide Web due to its
wide support and portability.
The format
supports up to 8 bits per pixel for each image, allowing a single
image to reference its own palette of up to 256 different colors chosen from
the 24-bit RGB color space. It also supports animations and
allows a separate palette of up to 256 colors for each frame. These
palette limitations make GIF less suitable for reproducing color photographs
and other images with color gradients, but it is well-suited for simpler images
such as graphics or logos with solid areas of color.
GIF images
are compressed using the Lempel–Ziv–Welch (LZW) lossless data
compression technique to reduce the file size without degrading the visual
quality. This compression technique was patented in 1985. Controversy over the
licensing agreement between the software patent holder, Unisys,
and CompuServe in 1994 spurred the development of the Portable Network
Graphics (PNG) standard. By 2004 all the relevant patents had expired.
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