Image analysis deals with discrete picture, obtained by a process of digitization. Through this process, losing some information is inevitable. Length of a curve belongs to this category. Since the existence of digital image there are many algorithms proposed for estimating the length of the curve. Length estimation in digital image is tied to the method of digitization. We chose four-neighborhood digitization in two dimensions. This digitization makes it possible for length estimator to apply the Vertex Chain Code. A trace contour algorithm is applied to extract the Vertex Chain Code. The output is used for global length estimation, namely maximum-length digital straight segments. In this paper we compare this global length estimator for both Freeman Chain Code and Vertex Chain Code.
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