A method and apparatus reliably and robustly decode single width bar codes that may be placed on a variety of materials. The decoding is independent of whether or not the bar code represents dark bars on a light background or light bars on a dark background. The decoder may be implemented either in hardware...http://www.google.com.tw/patents/US5537431?utm_source=gb-gplus-share專利 US5537431 - Method and apparatus for bar code reading and decoding
