n poorer image quality. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Protocols Chapter 2 GIF clearly offers some advantages over JPEG, but in the long term JPEG offers better image quality than GIF. Of course, eight-bit displays are rapidly disappearing from the landscape in favor of higher resolution monitors. For them, GIF has already become an academic argument because JPEG is a far better solution for image display. The Graphics Interchange Format (GIF) GIF defines a protocol designed to transmit raster-based graphic data that is independent of the hardware used to create or display them. GIF is defined in terms of blocks and subblocks that contain relevant infor- mation used to reproduce a graphic. CompuServe released GIF as a free and open specification in 1987. It soon became a global standard and also played an important role within the Internet community as users started to share graphics files. It was well supported by CompuServe's Information Service but did not require a subscription to CompuServe. The format was relatively simple and well documented. Like most graphic management tools, GIF compresses images to reduce the file size, using a technique called Lempel-Ziv-Welch (LZW) compression. Unisys holds a patent on the LZW procedure, which soon became a popular technique for data compression. GIF is not the only tool that relies on LZW; TIFF, described later, also includes LZW com- pression among its favored compression techniques. JPEG VS. GIF JPEG can typically achieve compression ratios of 10:1 to 20:1 without perceptible loss; 30:1 to 50:1 compression is possible with small to mod- erate visible artifacts, while 100:1 compression can be achieved- although quality suffers dramatically. By comparison, a GIF image loses most of the color information in the process of reducing the 24-bit image to the 256-color palette, provi