An algorithm for rotating images of objects represented as chain-code

An algorithm for rotating chain-coded images of objects by an arbitrary amount with little inherent distortion has been developed, and a program has been written to demonstrate its use. Chain code is a conveniently compact and efficient means of storing object outlines in computer memory, but with this coding scheme arbitrary rotations of coded outlines are difficult to perform. The algorithm presented not only allows for rotations of arbitrary angle, but has the additional advantage of allowing for rotation around any specified point in the image plane. The effectiveness of the rotation algorithm is discussed, and the results of its application to the rotation of a simple object are compared with the results obtained by rotating the original image of the object and reencoding its outline. Results show that distortions inherent in the algorithm are comparable with those obtained with encoding of a rotated original image