Although I have a perfectly good fingerprint reader on my Samsung Q1 Ultra Premium, I wanted to see if there was an option to use the front-facing integrated web-cam for logging in to my device. A little dose of early afternoon Google found me a potential solution called LemonScreen from KeyLemon. I just downloaded the free beta application and installed it on my UMPC that runs Windows Vista and gave it a quick test. Unfortunately, LemonScreen won’t work to replace the Windows logon, but you can use it to unlock your PC if you manually lock it or after a period of inactivity that you can specify.
In order to use LemonScreen, you first need to create a facial model, which is similar to enrolling your fingerprints on a reader. In this mode, the application continuously scans your face and offers instant feedback in the form a "face detection confidence" meter. Apparently, I have less of a face when wearing a hat, so I removed it and the confidence factor went up noticeably. After I got the confidence meter into the green, saved the facial model which also needed my Windows password.
Aside from removing my hat, I did some high-level testing of the recognition algorithm by turning my head in various directions. After wrenching my neck a few times, I realized that the confidence level was optimal when my head was positioned in the exact same way as enrollment, which I expected.
Since you can’t replace your Windows login with LemonScreen, I set the inactivity parameter to 60 seconds. Leaving the machine alone for a minute caused the device to log and LemonScreen then works in a scanning mode so you can log in via your webcam.
I tested the recognition five times over five minutes and the app routinely unlocked my UMPC with just a second or two of scanning. If for any reason the application doesn’t recognize your face, you can manually type in your Windows password at the bottom of the application; useful say if you don’t have your glasses with you and LemonScreen is looking for them. ;)
If you don’t want to set the inactivity timer, you can manually lock your machine with LemonScreen using an option in the tray icon. Ideally, this app would be much more useful if you could use it for your initial Windows login, but the developers are still working on that. While LemonScreen has limited settings and usage models for now, it appears to work well for those that want to lock a webcam-enabled PC and then log in with the camera.
I should also note that the app is geared for use on Windows 2000 and XP, although it appears to be running just fine on Vista in my case.