Before I started ripping the walls out of my house, I had a fingerprint scanner for opening the front door. That was cool, but wouldn't it be better if your front door could see you coming and automatically unlock itself?!

This screenshot shows face detection - the first step in face recognition. The color image is the unprocessed web cam image, the second shows a box drawn around the detected face and eyes, and the third is a normalized face, using a line through the eyes to calculate a rotation and orient the face vertically.

Luckily, detection is easy using Emgu, a C# .NET wrapper for the OpenCV image processing library. Most of the detection logic is translated from c++ examples I found with Google. The detection is done using Haar cascades and is faster than I expected - processing about 10 frames per second. The recognition part is much harder . . .