This report presents an algorithm for locating the cut points for and separatingvertically attached traffic signs in Sweden. This algorithm provides severaladvanced digital image processing features: binary image which representsvisual object and its complex rectangle background with number one and zerorespectively, improved cross correlation which shows the similarity of 2Dobjects and filters traffic sign candidates, simplified shape decompositionwhich smoothes contour of visual object iteratively in order to reduce whitenoises, flipping point detection which locates black noises candidates, chasmfilling algorithm which eliminates black noises, determines the final cut pointsand separates originally attached traffic signs into individual ones. At each step,the mediate results as well as the efficiency in practice would be presented toshow the advantages and disadvantages of the developed algorithm. Thisreport concentrates on contour-based recognition of Swedish traffic signs. Thegeneral shapes cover upward triangle, downward triangle, circle, rectangle andoctagon. At last, a demonstration program would be presented to show howthe algorithm works in real-time environment.

A novel and unconventional shape description scheme is proposed which captures the hierarchy of parts and medial descriptors. Both the parts and the medial descriptors are extracted simultaneously, in a complementary fashion, using a real valued function defined over the shape domain. The function arises out of both global and local interactions within the shape domain and it is related to an extension of a linear elliptic PDE with an integral term. The part hierarchies, extracted via level sets and watersheds of the function, are organized into proper binary trees, and the medial descriptors, extracted via ridges and watersheds of the function, are organized as rooted depth-1 trees. The medial descriptors (we named global skeleton) consist of two distinct medial abstractions. The limbs and prominent boundary features are captured in the form of conventional skeletons. Secondly, the coarse structure of the shape is captured in the form of a watershed region, which is a powerful tool in respect to both stability and representation of prominent shape properties. Additionally, as an important technical contribution that addresses part matching, the randomized hierarchy tree is introduced that endows the part hierarchy tree with a probabilistic structure.