The ambient light sensor doesn't seem to be correctly used in low light conditions.
In low light, with the phone "locked", just push the middle unlock button. The screen show the usual unlock screen, but at high brightness, for what seems to be a variable time (every time I do this), but not longer than 100-200 ms. Then the ambient light sensor starts to work, and reduces the display brightness.
This has only started since the black update. My Lumia 925 was working fine before, and now this display brightness problem has started. It only happens in low light conditions. If there is enough light (eg. daylight), the screen doesn't start with max brightness to begin with.
It doesn't matter if I'm using "glance" either. With this feature turned on or off, in low light conditions, this problem is the same.
I am now not using glance (I wasn't really using it before the update anyway), and I've set my screen brightness to a set value as a workaround.
OS version 8.0.10517.150
Solved! Go to Solution.
So I've played with my phone more ... and I don't think there is a big problem. If I move to a room that is darker, and wait a few seconds, the phone unlock screen isn't bright when I hit the unlock button. It seems the phone now needs longer time to get used to the light conditions it is in.
Maybe the Lumia was always like this, or maybe the ambient light sensor has a slower response time now, and isn't polled as often for its reading, like it was before. More likely is that as I have been playing with the glance screen, I've been locking and unlocking quickly, while walking around. The phone hasn't had enough time to update the ambient light settings.
Interestingly, with the glance set to interval, I can still wake up the interval screen when placing my hands on the screen. I had left my phone for sometime on its own, then I lifted it up. Either my fingers or the movement triggered the glance screen to turn on. Or its has a timer as such, and just happened to turn on at this point in time ! Who knows (well I'll search for more info about the new glance settings now).
So it looks like there is no problem. Either its always been like this, and I'm testing the ambient sensor polling to the limits by pressing the unlock button often. Or the polling rate has been reduced (maybe to help increase battery life).
Well after several weeks I find this issue annoying ! I think there really is a problem with the Black software release regarding the light sensor.
It just reacts too slow. Before the Black update, the reaction times were much better.
Sometimes in low light, the screen is just too dim, and it either increases the brightness after a few seconds, or if I move to more light then it corrects.
It seems that the light sensor is not polled enough, or something similar, and it doesn't seem to be polled before the screen is woken up. When someone presses the unlock button, the light sensor should be polled, the inital brightness calculated, and then the screen turned on. This doesn't seem to happen anymore.
To me, I find this "feature" a bug in the Black release.
It doesn't matter if I use the glance screen or not. I have the same issues regarding the screen brightness.
FYI: There have been a lot of app updates the last few days (> 10 updates). Glance was among them. I've made a quick check regarding the light sensor. It seems to be working correctly again
Which is of course great !