DIAGRAM FORMING UNIT

摘要

A digital system detects edges in a full tone picture by scanning and reproduces them in solid lines of controllable width to provide an outline drawing of the picture. Each line of video information produced by scanning the picture is digitised by an A-D converter. Each digital sample is compared to a digital sample delayed by a predetermined amount to generate a difference signal which is indicative of a change in the gray scale in a direction perpendicular to the scanned lines. The digitised samples of the video signal are stored in shift registers having capacity sufficient to store data representing a plurality of scan lines. Selected digital samples from the stored data are compared to samples of the line being scanned to detect changes in the gray scale in a direction parallel to the scanned lines. These detected changes in the gray scale are combined to generate a signal which operates a printer to generate a line drawing of the scanned picture.