Least-Squares Font Metric Estimation from Images

摘要

The paper discusses the problem of determining font metrics from measurements onimages of typeset text and develops least-squares procedures for font metric estimation. When it is known that kerning is not present, sidebearing estimation involves solving a set of linear equations, called the sidebearing normal equations. More generally, simultaneous sidebearing and kerning term estimation involves an iterative procedure in which a modified set of sidebearing normal equations is solved during each iteration. Character depth estimates are obtained by solving a set of baseline normal equations. In a preliminary evaluation of the proposed procedures on scanned text images in four fonts the root-mean-square set width estimation error was less than 0.1 pixel. A novel application of font metric estimation to text image editing is discussed. (Copyright (c) 1992 Xerox Corporation. All rights reserved.)