JPEG, GIFF/JIFF, BMP, and TIFF are the most commonly used formats
for storing still image files such as photographs, graphics, and
drawings. JPEG stands for Joint Photographic Experts Group and is
a standard for image compression.
However, some amount of data/detail is lost in the process. JPEG
therefore is characterized by a glossy compression technique for
still color images, just as MPEG is used for compressing motion
GIFF/JIFF stands for Graphics Interchange format, which is a bit-mapped
graphics file format.
Its storage is limited to about 256 colors as against 16 million
colors in JPEG. GIFF therefore is more suitable to store illustrations
rather than color photos.
Other popular formats for storing bit-mapped images are TIFF (Tagged
image file format), BMP,and PCX. You'll also see GIF and JPG. You
may be wondering what a bit-map is? A bit-map graphic is composed
of a pattern of dots (each dot containing bits of data). Vector
graphics, on the other hand, use geometrical formulas to represent
images. The latter can be scaled i.e. the object size can be changed
while maintaining its shape. Vector images are thus more flexible
than bit-maps. Also vector imageslook better on higher resolution
and require less memory. This brings us to the difference between
Paint programs and Draw programs. In Paint program the drawings
are represented as bit-maps. Draw programs, on the other hand, represent
images as vector graphics.
Why we need to convert images from one format to another?