Design Of Perimeter Estimators For Digitized Planar Shapes

Measurement of perimeters of planar shapes from their digitized images is a common task of computer vision systems. A general methodology for the design of simple and accurate perimeter estimation algorithms is described. It is based on minimizing the maximum estimation error for digitized straight edges over all orientations. A new perimeter estimator is derived and its performance is tested on digitized circles using computer simulations. The experimental results may be used to predict the performance of the algorithms on shapes with arbitrary contours of continuous curvature. The simulations also show that fast and accurate perimeter estimation is possible even for objects that are small relative to pixel size.