Patent ID: 8358433

Claim:
A method of revealing hidden content associated with printed content using a handheld display device, said method comprising the steps of: imaging an area of a printed substrate and generating image data using an image sensor of the handheld display device, the imaged area of the printed substrate containing the printed content but no hidden content; determining interaction data using said image data, said interaction data identifying a page description corresponding to at least part of the printed substrate; retrieving display data using the page description, said display data including the hidden content associated with the printed content; displaying, on an opaque touch-sensitive display screen of the handheld display device, display information at least partially based on said display data, said display information including the hidden content, wherein the opaque touch-sensitive display screen has real-time virtual transparency through the screen to the printed content from a user's perspective to provide a virtual window to the printed content, and wherein the opaque display screen additionally displays the hidden content in real-time as if it were printed on the printed substrate.