Compression and error sensitivity of two-dimensional facsimile coding techniques

Seven proposals were submitted to the International Telegraph and Telephone Consultative Committee (CCITT) for selection of a standard two-dimensional code as an extension of the current CCITT standard one-dimensional code. The CCITT specified the use of particular parameters and procedures to compare the candidate techniques on a quantitative basis. The compression ratio and error sensitivity of all seven coding techniques were measured for a wide range of operational conditions. For example, tests are performed with small K-factors for application to error-prone transmission over switched circuits, and also at infinite K-factor to simulate packet switching networks possessing error control. Particular attention is paid to the error detection/correction procedure to insure that the error sensitivity parameter is as realistic as possible. The essential differences between the seven proposed coding techniques are presented, and the measurement parameters and procedures are reviewed.