Storing data in a format that requires less space than usual. Compressing data is the same as packing data.
Data compression is particularly useful in communications because it enables devices to transmit the same amount of data in fewer bits. There are a variety of data compression techniques, but only a few have been standardized. The CCITT has defined a standard data compression technique for transmitting faxes (Group 3 standard) and a compression standard for data communications through modems (CCITT V.42 bis). In addition, there are file compression formats, such as ARC and ZIP.
Data compression is also widely used in backup utilities, spreadsheet applications, and database management systems. Certain types of data, such as bit-mapped graphics, can be compressed to a small fraction of their normal size.
Copyright © 1996-1998 Mecklermedia Corp.
Man unterscheidet grundsätzlich zwei Typen von Datenkompression:
Refers to data compression techniques in which no data is lost. The PKZIP compression technology is an example of lossless compression. For most types of data, lossless compression techniques can reduce the space needed by only about 50%. For greater compression, one must use a lossy compression technique. Note, however, that only certain types of data -- graphics, audio, and video -- can tolerate lossy compression. You must use a lossless compression technique when compressing data and programs.
Copyright © 1996-1998 Mecklermedia Corp.
Refers to data compression techniques in which some amount of data is lost. Lossy compression technologies attempt to eliminate redundant or unnecessary information. Most video compression technologies, such as MPEG, use a lossy technique.
Copyright © 1996-1998 Mecklermedia Corp.