Estimation of Linear Stroke Parameters using Iterative Total Least Squares Methods

Jan A. Van Mieghem, Hadar Avi-Itzhak and Roger D. Melen. SPIE Proceedings, 1661, Feb. 1992


In this paper we present an algorithm to enhance the accuracy of the estimation of the parameters of linear stroke segments in a two-dimensional printed character image. The algorithm achieves high accuracy in comparatively less computational time than most traditional methods. It is invariant under rotation and translation and no a priori information about the image is required. The Iterative Total Least Squares (ITLS) method begins at a randomly assigned initial approximation of the line parameters. A rectangular window is centered using the current stroke approximation, and a new line estimate is generated by making a total least squares fit through the pixels contained within the window. This is then repeated until convergence is reached. Adaptive adjustments of the window size and choice of profile can further improve the obtained accuracy. In addition, a `fast' ITLS method has been developed.