Just released!
- no extension needed
- no OpenCV needed
- detects multiple faces in one image
- handles different classifiers (also object classifiers)
This is a port of JViolaJones (http://code.google.com/p/jviolajones/) to PHP. The author of JViolaJones did a great job writing understandable code. Both thumbs up! PHP FaceDetector as well as JViolaJones can handle the classifiers shipped with OpenCV or trained with OpenCV. One classifier (haarcascade_frontalface_default.xml) is shipped with this software, so you don’t need to download or install OpenCV, although it is a great tool too.
See and download:
https://github.com/felixkoch/PHP-FaceDetector