Review of length estimators in 2D

Abstract

The practice of representing an image is usually in digitized form. This digitized format cause to apply discrete geometric to extract quantitative information such as feature size or length (V. Toh, C.A. Glasbey et al. 2003). Although because of digitization there is not any knowledge about the continuous shape, by assistance of discrete geometric estimators it is possible to obtain the feature size and often this involves curve length estimation. In discrete geometry features are categorized in to two groups, one is global such as area, perimeter and moments and the other is local such as tangents, normals and curvatures(Fran¸cois de Vieilleville, Jacques-Olivier Lachaud et al. 2005). The estimating these geometric features are based on their shape or curves. Shape is a major feature in visual databases such as image, graphics and video is shape. It is carries meaningful information about the associated visual objects. There are a variety of schemes for shape representation. One of the widely used schemes is chain code. It is used for coding purpose as well as for syntactical analysis of a digital line or curve(Yi Xiao, Ju jia Zou et al. 2001).