The information in an image file is encoded in a format which specifies the way the information is organized. Since image files are rather large, certain file formats "compress" the information in order to reduce the file size and provide for more efficient storage and data transmission. Some formats represent "lossy" compression in which some of the image data is sacrificed but usable for normal viewing. Some common image file formats are:

GIF (Graphics Interchange Format)- GIF format supports up to 256 colors (8 bits per pixel) and incorporates "lossless" compression resulting in manageable file size. Lossless means that the image is restored exactly upon decompressing the file. GIF images preserve all of the detail and color present in the original image.

JPEG (Joint Photographic Experts Group)- JPEG format supports full color (24 bits per pixel) but inorporates "lossy" compression. The original image cannot be exactly restored when the file is decompressed. Although image quality is degraded at the expense of file size, JPEG permits very small file sizes for even very large full-color images. It subdivides the image, averages the pixel values in each subdivision and saves only the relative differences within each subdivision.

TIFF (Tagged Image File Format)- TIFF provides the maximum quality at the expense of large file sizes and thus slow transmission of images. It supports full color (24 bits per pixel) images. TIFF images are compressed using "lossless" compression.

PICT- PICT format is commonly used among Macintosh graphics and page-layout applications as an intermediary format for transferring files between applications. It is most effective at compressing images containing large areas of solid color. RGB images can be PICT formatted using either 16 bit or 32 bit pixel resolution.

MPEG- MPEG is a digital motion picture format. It supports full-color, full motion video using a "lossy" compression resulting in quite compact files.