Surface having optically readable printed tags

Abstract

A surface having an optically readable pattern of dots printed thereon. Each tag has a background pattern defining discrete areas. The background pattern is common to all tags. Each tag further has coded data positioned within the discrete areas. The coded data is represented by a plurality of optically readable marks positioned according to an encoding scheme. The background pattern is also distinguishable from the coded data.

1 . A surface having a plurality of optically readable tags printed thereon, each tag comprising:
 a background pattern defining discrete areas, said background pattern being common to all tags; and   coded data positioned within said discrete areas, said coded data being represented by a plurality of optically readable marks positioned according to an encoding scheme,   wherein the background pattern is distinguishable from the coded data.   
     
     
         2 . The surface of  claim 1 , wherein each discrete area further contains features usable by an optical reader to determine a perspective distortion of the tag. 
     
     
         3 . The surface of  claim 1 , wherein each tag further comprises orientation information positioned within said discrete areas, the orientation information being indicative of a rotational orientation of the tag. 
     
     
         4 . The surface of  claim 1 , wherein the coded data in each discrete area is redundantly encoded by the plurality of marks. 
     
     
         5 . The surface of  claim 4 , wherein the coded data is encoded by Reed-Solomon codewords. 
     
     
         6 . The surface of  claim 1 , wherein the coded data within each discrete area identifies a page identity which is common to all tags on the surface. 
     
     
         7 . The surface of  claim 6 , wherein the coded data varies between respective tags. 
     
     
         8 . The surface of  claim 1 , wherein said tags are printed with an infrared absorbing ink.