The GIF and JPEG formats covered in this workshop are raster images. Scanners Flatbed scanners and slide scanners are used to reformat images from analog to digital format. Vector Images Images based upon mathematical formulas rather than pixels. Considered line art, vector images are resolution independent and have yet to be commonly used in web pages. Both formats operate across platforms and are best described as methods which compress, albeit in different ways, image size for high-speed transfer.
Images contain a lot of data which makes compression necessary.
Otherwise, if images are not compressed, files take too much time to load and use a considerable amount of storage space. Both GIF and JPEG offer different compression rates and it is important to know which format to use for the type of image you have. Graphics Interchange Format or GIF is based upon a table of 256 colors and is best used for icons, reduced color images, and drawings. When it finds repeated sequences it places them into an index for retrieval later. For example, an exact circle is stored in half since it repeats itself.