Face detection form picture and replacement

i want to build an script that has following features...

On the images there is a sign on the face to substitute with the face that
the user will upload

Want to detect face from picture and replace by other face....this is the main criteria of this project.




when i upload a pic form my local computer... this script first detect the face from existings picture and then replace this part by uploaded face.


Please help me how to do it....this is very urgent.

From
Arnab Mallick

Please stick to the PHP specialists forum to ask difficult questions like this.