It's completely logical for screen to become white if it notices darkness (ambient light sensor) and the situation requires better illumination (like face recognition). I have already used white screen (with Notes or Sketch open) as a weak light. Just not to stumble in the room.
It could also be possible to check whether shutter of back camera is open and use its flash light (not correct direction, but still it could make situation better). I would prefer to have one 8MP camera with flash instead of 3MP+5MP with flash, rotatable to either front or back of N900. It would give better experience in many situations.

posted this here in the forum some time ago.

http://www.mobioproject.org/news/the...n-a-nokia-n900

Have you seen n900's front camera? Even regular artificial light is not enough for it, not to mention dim white screen..

1. How have you seen it? Maybe, I overlooked it, but I have never taken a photograph/video with front camera.

2. One more reason to have one rotatable camera instead of two fixed. Or, just ask the user to look onto the back camera until the device says (with sounds of speakers, vibration, or blinking of the two LED): "Face recognised!"
Even it would be a substantial progress.

Try "mirror" app.

the front camera is good enough to detect your face at mild light, it does not need to be super crisp

The camera has to be good enough to tell apart two twins in case one of them "steals" Nokia from another.
Though it's theoretically impossible.

OK, then make it scan the fingerprints as well, need to put your finger up close to the camera

how about iris scan?

Chipping in with an idea here. You use the back camera instead, that way you'll have access to leds if you need them. Once it sees your face, the program would flash the camera leds in a rapid succession to let you know it worked. A tad harder, but the front camera plainly sux.