The present invention discloses a method for producing graphical indicators and interactive systems for utilizing the graphical indicators. On the surface of an object, visually negligible graphical indicators are provided. The graphical indicators and main information, i.e. text or pictures, co-exist...http://www.google.de/patents/US7669774?utm_source=gb-gplus-sharePatent US7669774 - Method for producing indicators and processing apparatus and system utilizing the indicators
