Encoding image edges as a curve collection

We present a lossless compression algorithm for coding image edges. First, we determine an optimal order of all edges by solving a traveling salesperson problem and then code efficiently the starting point of each edge with respect to one of the two end points of the previous edge in the order. Next, we code the remaining edge points using a modified chain difference coding algorithm. This algorithm reduces entropy of the source. Finally, we use LZW for entropy coding of the output. We provide experimental results to compare the coding rate of our algorithm for some natural images with arithmetic coding of chain difference code and JBIG.