Android: detect brightness (amount of light) in phone's surroundings using the camera?

Question

The following applies to the Android operating system.

I am trying to estimate how dark (or light) it is in the room where the phone is located using the camera.

Answer 1

The big deal at wanting to nail the brightness down is to figure out how HTC is doing it in their camera.apk . Because the stock Android Camera app is horrible for overexposure especially for the DINC.