Tracking lines through noise

Reports work done in an effort to improve the following of line structured data on images of poor quality engineering drawings. There is a substantial literature on processing line drawings; Smith (1987) gives a review of pixel level methods and Joseph (1968) references higher level approaches. These concern binarised images, and their application to poor quality images is limited to overcoming faults by post processing. On the other hand, there is a still more substantial literature on aggregation of edges into lines or curves (see Rosenfield and Kak, 1982), which concerns grey level images and images produced by transforming them through various filters. Much of this work deals with the recovery of weak or detailed features from noise and is applied to images of quite general scenes. This dichotomy between processing line drawings and analysing general scenes may have arisen because of the very large image sizes of the former compelled the binarisation of images before storage, whereas the generality of the letter forbade it. The present work spans the two approaches, bringing insights to both