An apparatus for determining the location and content of data blocks on a mailpiece includes a computer connected to a structure for obtaining a digital bit map image of an outer surface of a mailpiece. The computer includes structure programmed for: finding each run of a plurality of black bits of each scan line of the bit map image and determining if any bit thereof neighbors at least one black bit of another scan line; combining the found run with each neighboring bit to form a piece; assigning a descriptive value to a block having at least one piece and comparing the descriptive value to a list of values to determine which type of data block the block having the descriptive value is.