I am using OpenCV Haar Algorithm to track the Head and overlay an image over the Head.  

What I am doing is saving frames generated by camera and overlaying image over each frames.  

And time is not a constraint as I am not doing it Real-Time. 

My code is working fine for say 45 degree of left and right rotation of Head.  

But I need something which will track up to 90 degree of rotation. 

Even I got many reference of OpenCV functions and [link to estimate Head Pose](http://www.morethantechnical.com/2010/03/19/quick-and-easy-head-pose-estimation-with-opencv-w-code/)

Please provide me some reference. Code Examples will be cool.  

Thanks in advance