Real-Time Recognition of Handprinted Text

Describes a program, written in IBM 360 Assemble Language, that allows the user of an on-line computer to print data and directives on the RAND Tablet with a special pen and have them recognized and displayed immediately. The scheme recognizes 53 letters, numbers, and symbols in a wide variety of printing styles, resquiring only the usual conventions followed on coding forms. High-resolution point-by-point pen location data are gathered, displayed on the cathode ray tube screen, and analyzed while the character is being written or drawn. An average 100 data poiints per stroke (one each 4 msec) are collected, filtered, and thinned. A stroke is identified by such clues as sequence of directions, corners, and end-point location, and also by contextual clues when necessary. Multiple stroke symbols are recognized by the identification and relative location of the constituent strokes, regardless of the order in which they are written. The pen track is displayed until the character is recognized, and is then replaced by a standard hardware-generated version of the character. Previously written material remains on the display until removed. Changes, insertions, and deletions are easier than with pencil and paper. Experiments with groups of programmers, engineers, and secretaries indicate that a half-hour training period is suffcient, with 90 percent immediate recognition by the system. The scheme is in daily use in an expermental problem solving system at RAND.