Form-based localization of the destination address block on complex envelopes

Address block localization on mail pieces is an important task in postal automation. Unlike personal letters, business letters or postcards which have a high degree of global spatial structure among a limited number of entities, mail pieces of magazines and advertising do not have a preferred position of the address block which can be pasted in an arbitrary position and orientation. Items packaged in clear plastic, allowing the underlying print to show through, may cause further problems, as well as graphics, pictures and other printed text on such covers which also make the address block localization more complicated. In this paper, we present an approach for automatically locating the address block on covers of magazines, advertising letters and newspapers based on the recognition of the structure of a German address. First, we use a thresholding technique to decompose the image into smaller blocks. Then, these blocks are classified into characters and large characters. Afterwards blocks are searched which might be a corner of an address block. Starting from these blocks adjacent blocks are combined to connected regions line by line. These regions are candidates for an address block and are assessed in the last step. Heuristic rules and typical features are used to identify the correct destination address block among these candidates. Experimental results using images of different magazines, newspapers and advertising letters are given. Performance and speed are also indicated.