Some image file format definitions, as found on whatis.com and searchWebmanagement.com
TIFF
TIFF (Tag Image File Format) is a common format for exchanging raster graphics (bitmap) images between application programs, including those used for scanner images. A TIFF file can be identified as a file with a ".tiff" or ".tif" file name suffix. The TIFF format was developed in 1986 by an industry committee chaired by the Aldus Corporation (now part of Adobe Software). Microsoft and Hewlett-Packard were among the contributors to the format. One of the most common graphic image formats, TIFF files are commonly used in desktop publishing, faxing, 3-D applications, and medical imaging applications.
TIFF files can be in any of several classes, including gray scale, color palette, or RGB full color, and can include files with JPEG, LZW, or CCITT Group 4 standard run-length image compression.
JPEG
A JPEG (pronounced JAY-peg) is a graphic image file created by choosing from a range of compression qualities (actually, from one of a suite of compression algorithms). When you create a JPEG or convert an image from another format to a JPEG, you are asked to specify the quality of image you want. Since the highest quality results in the largest file, you can make a trade-off between image quality and file size. Formally, the JPEG file format is ISO standard 10918. The JPEG scheme includes 29 distinct coding processes although a JPEG implementer may not use them all. JPEG is an acronym for Joint Photographic Experts Group, the committee that established the baseline algorithms.
Together with the Graphic Interchange Format (GIF) and Portable Network Graphics (PNG) file formats, the JPEG is one of the image file formats supported on the World Wide Web, usually with the file suffix of ".jpg". You can create a progressive JPEG that is similar to an interlaced GIF.
GIF
The GIF (the original and preferred pronunciation is DJIF; it stands for Graphics Interchange Format) is one of the two most common file formats for graphic images on the World Wide Web. The other is the JPEG.On the Web and elsewhere on the Internet (for example, bulletin board services), the GIF has become a de facto standard form of image. The LZW compression algorithm used in the GIF format is owned by Unisys, and companies that make products that exploit the algorithm (including the GIF format) need to license its use from Unisys. In practice, Unisys has not required users of GIF images to obtain a license, although their licensing statement indicates that it is a requirement. Unisys says that getting a license from them does not necessarily involve a fee.
The GIF uses the 2D raster data type and is encoded in binary. There are two versions of the format, 87a and GIF89a. Version 89a (July, 1989) allows for the possibility of an animated GIF, which is a short sequence of images within a single GIF file. A GIF89a can also be specified for interlaced GIF presentation.
A patent-free replacement for the GIF, the Portable Network Graphics (PNG) format, has been developed by an Internet committee and major browsers support it or soon will. Meanwhile, many GIF down loaders and Web site builders on the Web continue to be ignorant of or indifferent to the requirement to get a license from Unisys for the use of their algorithm.
bit mapA bit map (often spelled "bitmap") defines a display space and the color for each pixel or "bit" in the display space. A Graphics Interchange Format and a JPEG are examples of graphic image file types that contain bit maps.
A bit map does not need to contain a bit of color-coded information for each pixel on every row. It only needs to contain information indicating a new color as the display scans along a row. Thus, an image with much solid color will tend to require a small bit map.
Because a bit map uses a fixed or raster graphics method of specifying an image, the image cannot be immediately rescaled by a user without losing definition. A vector graphics graphic image, however, is designed to be quickly rescaled. Typically, an image is created using vector graphics and then, when the artist is satisfied with the image, it is converted to (or saved as) a raster graphic file or bit map.
