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How the hell does Auto-Brightness work?

Wow, how are you all so fail at this?

The slider doesn't indicate the current brightness level. It indicates the user's desired brightness level. If auto-brightness is turned off, that's exactly what the screen brightness will be.

If auto-brightness is turned on and you are using an iPhone 4, it will adjust the screen brightness within a certain range of the user setting. The slider will not move. The screen can actually get brighter than the users setting (unless it's maximum obviously).

If auto-brightness is turned on and you are not using an iPhone 4, the screen brightness can not be more than the users setting.
 
Eso said:
Wow, how are you all so fail at this?

The slider doesn't indicate the current brightness level. It indicates the user's desired brightness level. If auto-brightness is turned off, that's exactly what the screen brightness will be.

If auto-brightness is turned on and you are using an iPhone 4, it will adjust the screen brightness within a certain range of the user setting. The slider will not move. The screen can actually get brighter than the users setting (unless it's maximum obviously).

If auto-brightness is turned on and you are not using an iPhone 4, the screen brightness can not be more than the users setting.
Click to expand...

This.

I personally keep my auto-brightness turned off as it dims the screen when I don't want it to be sometimes.
 
WhySoSerious said:
So, i assume that when i turn my phone on in a dark room, the auto-adjust will lower the brightness down to....say...50%; however, it won't. It stays at 100% by no choice of my own.
Click to expand...

First, the subtle changes in brightness will probably be easier to notice at lower levels. Turn it down.

Also, I could be wrong, but I don't think the slider ever actually moves by itself. It sounds like you're hovering over the Settings app waiting for the slider to move. Close out of the Settings app (after turning the brightness down), and use it as you normally would in various lighting conditions. You should notice the screen brightness change by itself periodically.
 
FWIW, I've always assumed the adjustment slider was to set the minimum brightness of the screen... That it would never drop below that, but if I was in a very bright room or outside, the screen would get brighter so I could actually see it.

It appears to work that way for me, never really thought that it might dim lower than my settings.
 
WhySoSerious said:
do you not comprehend the original post?

I have the brightness set to 100% with auto-adjust set ON.

So, i assume that when i turn my phone on in a dark room, the auto-adjust will lower the brightness down to....say...50%; however, it won't. It stays at 100% by no choice of my own.

That's the problem, Mmm-kay pumpkin.
Click to expand...

I am pretty sure that the others are correct. If it is set to 100%, it will not change. It only changes if you set it below 100%.
 
Grimes said:
FWIW, I've always assumed the adjustment slider was to set the minimum brightness of the screen... That it would never drop below that, but if I was in a very bright room or outside, the screen would get brighter so I could actually see it.

It appears to work that way for me, never really thought that it might dim lower than my settings.
Click to expand...

It works differently for me. On my iPhone 4 the slider can't possibly be the minimum brightness because as soon as I turn on auto brightness indoors the screen brightness immediately drops. The earlier explanation seems to correspond better with my experience, namely that in auto brightness mode the slider is used as a not-to-exceed brightness.

Autobrightness doesn't work that well for me. I find the time it takes to adjust to be too long. Sometimes I switch on my phone and after about 10 or 20 seconds it suddenly seems to decide to adjust the brightness and I get an abrupt change. I don't mind the abrupt change because it's always in the appropriate direction but I don't understand why it couldn't read the light sensor and set the screen brightness appropriately as soon as I switched it on rather than having the screen at the wrong brightness for those 10 or 20 seconds.

- Julian
 
WhySoSerious said:
do you not comprehend the original post?

I have the brightness set to 100% with auto-adjust set ON.

So, i assume that when i turn my phone on in a dark room, the auto-adjust will lower the brightness down to....say...50%; however, it won't. It stays at 100% by no choice of my own.

That's the problem, Mmm-kay pumpkin.
Click to expand...

The screen will get brighter and dimmer, but the actuall bar will never move, don't go by what the bar says. If your indoors and it's too bright, lock the phone by pressing the power button on the top then unlock it again and you should see the screen dim some.
 
i wish you could set a min and a max... i have it set around 50% but it gets wayyy to dim in a dark room but looks great in light. i don't wanna turn it up and drain my battery... i just want it not to dim as much :(
 
It does not work for you, because it sets the slider to the right, which is the maximum brightness. You have to move approximately way.I think that sets the minimum brightness. Try it.
 
It dims in the dark.

You won't notice any change if your brightness is at 0% and hardly you'll notice if is at 100%.

If you are in a dark room try to set the bar at 50% and press the auto-brightness and you'll see the changes istantly.
 
2 pages and no conclusions?

I noticed auto-brightness doesn't affect the lock screen on ip4...most annoying when checking the time in dark places and being blinded.

I prefer to stick to adjusting manually. SBSettings brightness slider was by far the most used feature on my 3g. I suppose keeping settings open to the brightness page and doubletapping to it isn't thaaaat hard.

The ideal solution IMO: have the volume rocker control it under certain circumstances like when the home button is held down...but that'll never happen I'm sure.
 
dishwashersafe said:
2 pages and no conclusions?
Click to expand...

Isn't the conclusion (a) that the auto-brightness (AB) isn't working for the OP because he has the slider at 100% and if he notches it down a bit then he should see AB doing something, and (b) that he shouldn't be expecting to see the slider moving because of AB because AB changes the screen brightness but it doesn't move the slider about? A few people have said these things and no one has disagreed so those seem pretty solid conclusions to me.

The area where people are saying contradictory things is on what the slider does when AB is set. Some people claim it's a minimum setting and AB won't go below the brightness set on the slider and others say it's a maximum setting and AB won't go above the brightness set on the slider. I'm with the second school of thought, it's a maximum limit for the brightness.

I can disprove the minimum-brightness theory within seconds on my iPhone. I go to the brightness page in settings, set brightness to some value (say 50%) and then in a slightly darkened room turn on auto-brightness. The screen immediately goes dimmer. If the slider was used as the minimum brightness setting then the screen couldn't possibly go dimmer than the current setting when I engage AB.

- Julian
 
mcdj said:
I would kill for a shortcut to the brightness slider in the subdock.
Click to expand...

Then jailbreaking is right for you. SBSettings is amazing and I miss it bc the ip4 jb isn't out yet. All you do is slide your finger at the top of the screen whenever and have shortcuts to a variety of things Inc. Brightness.
 
JulianL said:
Some people claim it's a minimum setting and AB won't go below the brightness set on the slider and others say it's a maximum setting and AB won't go above the brightness set on the slider. I'm with the second school of thought, it's a maximum limit for the brightness.
Click to expand...

I've already answered this.

First of all, what is the point of dimming an LCD screen? To save power! Auto-brightness was designed so that even though the user sets the brightness to a certain level, the phone can dim the screen a bit when in a dark area to save battery power. This is how every iPhone up until the 4 behaves - the brightness slider is the maximum brightness.

With the iPhone 4, auto-brightness is much smarter. Depending on the ambient conditions, it can actually make the screen brighter if warranted. It will obviously still make the screen dimmer in a dark area. However, in a very bright room (lots of glare) or in direct sunlight, the screen actually needs to be brighter to read it well. Auto-brightness on the iPhone 4 will do just that.

Perhaps the iPhone 4 uses a better light sensor; perhaps LCD battery power isn't as much of an issue with the bigger battery and better battery life. It doesn't matter, auto-brightness on the iPhone 4 works much better - the brightness slider is more of an average brightness.

The end (and no, auto-brightness will never move the slider).
 
Eso said:
Perhaps the iPhone 4 uses a better light sensor; perhaps LCD battery power isn't as much of an issue with the bigger battery and better battery life. It doesn't matter, auto-brightness on the iPhone 4 works much better - the brightness slider is more of an average brightness.
Click to expand...
Hmm. Maybe my unit is faulty then. I've never owned any other iPhone but auto brightness on my iPhone 4 is pretty rubbish. It takes ages to read the sensor and adjust the brightness. I can get my phone out on a sunny day, switch it on, and stay looking at the home screen. It takes a full 15 seconds or so of doing nothing, just holding the phone, and then suddenly the phone will decide to adjust the brightness. The same happens if I launch an app immediately, it seems to take about 15 seconds for the phone to decide to adjust the screen to the appropriate level of brightness.

I can understand why it might not take a single reading within milliseconds of switch on and use that as the current value for ambient light level but a 15 second delay? If you're making a phone call then it's probably just at the point when you've finished navigating the inappropriately dimmed screen to select the contact and initiate the call when the phone then finally decides to adjust the level for daylight conditions.

I need to go into an Apple store and play with some of the display models, covering up the sensor so they think it's dark, switching them off, and then back on again in the light, to see whether all units behave this way or whether I have a faulty unit.

- Julian
 
I've formulated my own conclusion:

No one here knows sh** about how auto brightness works, so i just put it at 100% brightness and turned auto-adjust OFF.

Ya, i love my screen bright, eat it. :cool:
 
I think the auto brightness sucks. I turn it off immediately whenever I get a new phone or restore. It seems whenever I leave it on the screen constantly flickers. Reminds me of my old MacBook drove me nuts on that too.
 
WhySoSerious said:
Seriously, how do you get it to work? I have it turned on and the slider is all the way to the right (most bright). However, when I'm sitting in the living room where it's really dark at night and turn my phone on, it stays at 100% brightness.....it doesn't "auto" down.
Click to expand...

Try to set the brightness to lower than 100%
when under auto brightness, it will dim down only to the minimum brightness u set in the brightness slider. So if u set minimum to 100%, it will still show 100% brightness even in dark room and will not dim down. The other thing I notice is that it is not very responsive to change, so u hv to give it a few seconds for it to change the brightness. You can also lock/unlock to set the brightess to the ambience. Hope tis helps
It does work for mine but the algorithm used in iPhone is not intuitive and responsive to ambience change and as such does not provide a adaptive experience to users. I should say it works but not to my expectation. If tuning down the slider to less than 100% still does not work for u, then your iPhone ambience light sensor might b faulty and need to send for repair
 
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