what actually moves is not document content but rather an image of the document's content. This is important, because there is no element of flexibility inherent in this system that allows the receiver to make immediate and easy changes to the document. The image must be converted into machine-readable data, a capability that is just now becoming possible with optical character recognition (OCR) software. As imaging technology advanced and networks grew more capable, other technological variations emerged. The marriage of the copy machine and the modem yielded the scanner, which allows high-quality images to be incorporated into documents or stored on a machine- accessible medium such as a hard drive. Other advances followed. The emergence of high-quality television (HQTV) coupled with high-bandwidth, high-quality networks led to the development and professional acceptance of medical imaging applica- tions, with which diagnosis-quality X-ray images can be used for remote teleradiology applications. This made possible the delivery of highly spe- cialized diagnostic capabilities to rural areas, a significant advancement and extension of medicine. Equally important are imaging applications that have emerged for the banking, insurance, design, and publishing industries. Images convey enormous amounts of information. By digitizing them, storing them online, and making them available simultaneously to large numbers of users, the applications for which the original image was intended are enhanced. Distance ceases to be an issue, transcription errors are elimi- nated, and the availability of expertise becomes a nonproblem. There are downsides, of course. Image-based applications require expensive end-user equipment. Image files tend to be large, so storage requirements are significant. Furthermore, because of the bandwidth- intensive nature of transmitted image files, network infrastructures must be reexamined. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 