Shape Comparison
Shape comparison has always been an important topic in computer vision. Since the VCC is invariant under translation, rotation, mirroring transformation, and starting point normalization, to determine if two curves have the same shape, it is only necessary to see if their chain elements are equal. For instance, the chains of the shapes in the Fig. 5.22b, and h (which represents the "fern leaf") are equal.
Now, how do we compare the chain codes of any two shapes to measure the similarity between them? Since the length of chains may be different, we cannot use any method of those described in Chapter 3 (Mathematical Methods for Similarity). So we well use a new method called string edit distance to match two chain codes or any two strings.