Bar code reading method and apparatus which is insensitive to scanning speed and to minor variations in width, caused by inaccurate printing, between like bars and spaces and which is suitable in particular to hand held manual scanners. The width of all the bars and spaces in a bar code are measured...http://www.google.es/patents/US4687912?utm_source=gb-gplus-sharePatente US4687912 - Bar code reading method and apparatus
