Glasses-free 3D experience now comes to Apple iPad 2 courtesy a group of French researchers who used the front-facing iPad 2 camera to gauge how a user is looking at the screen.

PC Magazine reported that the French group Engineering Human-Computer Interaction Research Group achieved the feat on iPad 2.

The group uses a technology called Head-Coupled Perspective (HCP) which uses the front-facing camera as a head-tracker. It gauges the user's head position in and accordingly adapts the perspective of 3D scene.

However, a patent filing by Apple revealed that it is working on a glasses-free 3D technology. In Dec. 2010 Apple was accorded a U.S. patent that relates to a technology allowing multiple users to view 3D images on a screen, sans a 3D glass.

The project, titled Three-dimensional display system, ascertains the position of a viewer and determines the left and right eye locations, and then uses the information to navigate the pixels to a particular spot on screen which reflects it back to respective left and right eye locations.

The technology is based on autostereoscopic displays - a term that defines the technology that renders 3D images without the use of glasses. The technology uses a reflective surface for display.

Here is a video of the HCP technology as demonstrated by Human-Computer Interaction Research Group: