Archive for March, 2008

Face detection using Flash and C++, revisited

Thursday, March 6th, 2008

Over the past few months I’ve been asked several times for the code for face detection in Flash. So I’ve taken some time to make a short demo application, grabbed from my original Virtual Mirror game (see my two previous blogs).

Here’s what it does: Flash grabs the webcam image every 60ms, and sends it using a socket connection to a separate C++ server that runs on your localhost. The server uses the OpenCV software library to detect faces, using a haar classifier cascade. When it detects one or more faces it sends the result (coordinates) back to Flash. There, Flash draws a transparent box or image at the coordinates of the face, like this:

ActionScript3 + C++, Face detected

What makes this cool is that you can perform quite complex image analysis (at least something you can’t easily do in Flash), and use this data on a platform that is highly suitable for multimedia development (animation, sound, nice graphics, etc).

The demo only handles one face now, but this could be easily expanded.


At the moment there are no installation instructions included. If you need help you can contact me, or wait untill I create the instructions (which I will) :)
A few quick pointers to get you past some obstacles:

  • Binary: You probably have to add the folder you run the .swf from as trusted directory in your Flash settings. Otherwise you get a security / sandbox violation error.
  • Binary: Start the server before starting the .swf (client). The .swf tries to connect to the server when it starts.
  • Binary: The needed OpenCV dll’s and .xml file for face detection are included in the same folder.
  • Source: (Server) If I remember correctly, only pthread is a required dependency. UPX is a file packer for releasing, Visual Leak detector can be turned off if you don’t want to use it.
  • Source: (Server) Additional dependencies you should include when compiling/linking: wsock32.lib cv.lib cxcore.lib highgui.lib

Last note: This was both my first AS3 and C++ project, I’m always open to suggestions, improvements and cool new ideas. Also, when you find this code useful, I would appreciate it if you’d drop me a line.