How to create mobile apps that can recognize location/orientation of 2D imges from the CAM

I am interested in finding out how mobile applications can recognize the location and orientation of a pre-determined 2D image/logo/glyph via live video from the camera.

For iPhone or And开发者_开发技巧roid, what libraries are used, and more importantly, are there any examples out there that demonstrate this?

Thanks!

Take a look at openCV and face detection and Haar classifiers