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 picture files.
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?
Conversion rules:
To explain how format conversion is carried out here’s an example:
If you want to change BMP to GIF, follow the same procedure except that in Save as Type box click on “Graphics Interchange Format (.gif)”
Once an image has been converted from one format to another, say GIF to JPEG, some of the information is lost. You can’t go back to the original file. Therefore it is always advisable that you make a copy of the original file before converting it.