Head-movement controlled human-computer interface

Among us there are people form whom operating a computer mouse or a keyboard is impossible due to   their   disabilities.   You   can   help   them   by   creating   an   application   allowing   for   hands-free  communication  with  the  computer.   Ttask  is  to develop a  method for  detecting   and  interpreting  certain head movements in order to browse through the image gallery, change the sizes of the photos,  rotate them... Feel free to add other functionality of the application.