Method and apparatus for locating and decoding a postnet forwarding bar

Abstract

A method and apparatus for locating multiple bar codes in a field. The apparatus includes a microcomputer programmed to detect the existence of bar codes in location cells in the field and then apply a location score to each location cell. Based on the scores assigned to the location cells, a particular location cell is selected and the location cells surrounding the selected cell are analyzed to determine whether they might contain a bar code segment. A location cell that is determined to be sufficiently likely to contain a bar code segment will be appended to the first selected location cell. In this manner, a bar code in the field can be located. The determination of whether the located bar code is a primary or a secondary bar code is made by further analyzing the located bar code. The further analyses may be to determine the located bar code's length, whether it has a predetermined prefix, or whether it has a predetermined pattern of descenders from its constituent line segments. A preferred embodiment of the inventive method and apparatus analyzes the image recorded in the field to locate areas containing Postnet bar codes. The number of bars in each Postnet bar code found in the field is then counted and a determinatinon is made as to whether the number of bars in the Postnet bar code equal a valid number of bars. If the field contains only a bar code containing a valid number of bars, that Postnet bar code is decoded to provide a valid ZIP code. If, however, a Postnet bar code is found in the field that does not contain a valid number of bars, the Postnet bar code is flagged as a forwarding Postnet bar code. The Postnet portion of the Postnet bar code is then decoded to provide a valid forwarding ZIP code.