90 ABSTRACTS OF PAPERS ACCEPTED FOR PUBLICATION

An Asynchronous Thinning Algorithm. THEO PAVLIDIS. Bell Laboratories, Murray Hill, New Jersey 07974.

Received October 2, 1981; revised December 17, 198 I

A problem common to many areas of pictorial information processing is the transformation of a bilevel (two-color) image into a line drawing. This paper discusses the first step in such a process: transformation of the bilevel image into another bilevel image that is thin. An algorithm is proposed that can be implemented in either parallel or sequential fashion, and therefore is suitable for a mixed operation where a group of processors operate in parallel with each one examining sequentially the pixels of a part of the image assigned to it. It is possible to process images in pieces and thin correctly parts that are intersected by the dividing lines. Therefore the method can be used on large images, such as maps and engineering drawings. The algorithm may also be run with certain options that label the thinned image so that exact reconstruction of the original is possible.

Undersrunding Engineering Drawings. ROBERT M. HARALICK AND DAVID QUEENEY. Departments of Electrical Engineering and Computer Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 2406 I.

Received November 12, 1981; revised February I I, 1982.

Understanding the three-dimensional objects depicted in the orthographic views employed in engineer- ing drawings can be achieved by solving a sequence of three consistent labeling problems. The constraints used in the engineering drawings are stated giving the translation to the constraints of the consistent labeling problems, and illustrating the computer solution by executing an appropriate tree search.

Detecrion of Moving Edges. SUSAN M. HAYNES AND RAMESH JAIN. Intelligent Systems Laboratory, Department of Computer Science, Wayne State University, Detroit, Michigan 48202.

Received November 1 I, 1981; revised March 3, 1982.

A technique requiring only two frames is presented for finding time-varying edges in a dynamic scene. The frames need not be contiguous. The proposed operator picks up moving edge points which are not easily detected with simple static-edge operators. The operator includes both change and edge detection in a way which improves overall performance. Also presented are arguments against the use of three-dimen- sional operators for scenes where the third dimension is temporal rather than spatial.

Fust Algorifhms for Estimuting Locul Imuge Properties. PETER J. BURT. Image Processing Laboratory, Electrical, Computer, and Systems Engineering Department, Rensselaer Polytechnic Institute, Troy, New York 12181.

Received February IS, 1982

A common task in image analysis is that of measuring image properties within local windows. Often the usefulness of these property estimates is determined by characteristics of the windows themselves. Critical factors include the window size and shape, and the contribution the window makes to the cost of computation. A description is given of a highly efficient procedure for computing property estimates within Gaussian-like windows. Estimates are obtained within windows of many sizes simultaneously.

Approximuting Point Set Imuges by Line Segments Using (I Variation of the Hough Transform. PHILIP R. THRIFT AND STANLEY M. DUNN. Computer Vision Laboratory, Computer Science Center, University of Maryland, College Park, Maryland 20742.

Received February 24, 1982.

A transform method is presented for the detection of curves in noisy point-set images and is used to detect line segments in such images. The results of this transform are compared to results from the Hough transform.