Detection and separation of symbols connected to graphics in line drawings

Presents a technique for the detection and separation of symbols connected to graphics in line drawings. The approach is based on a special image representation, that the authors call graph representation. The graph representation is especially convenient for line-like images, since it decomposes the line structure into `edges´ and `nodes´, that formalise the intuitive notions of `line´ and `crossing point between lines´. In this way, well-known algorithms from graph theory can be used. The graph is searched for characteristic sub-graphs, revealing the presence of symbols or noisy objects overlapping lines. Each symbol candidate is accurately processed, in order to make the area of its connection to lines as regular as possible. Actually, two different algorithms have been designed to perform this task: one for symbols crossing lines and the other for symbols only touching lines. Both of them are rotation invariant