ENCODING OF TELEWRITING SIGNALS BY A RING-SHAPED BIT ASSIGNMENT TO MOVEMENT VECTORS.

Abstract

This paper describes a new DPCM coding method for telewriting signals using two dimensional properties of a line drawing and variable length coding. In DPCM coding, the movement vectors, the differences between successive addresses of sampled points, are transmitted. Variable length coding of telewriting signals is based on the following: -the coordinate domain in which the values of dx and dy of the movement vectors exists is divided into several regions according to the frequency of occurrence of dx and dy values. -different code-word length is applied to indicate dx and dy values according to the region to which the values belong. Simulation experiments using actual handwriting signals, show that this coding method achieves coding efficiency approximately 15% higher than conventional coding methods.