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Brightness changes too frequently in

asked 2014-12-23 12:41:13 +0200

Valerij gravatar image

Hello! After update to Vaarainjärvi screen brightness changes too frequently. Even when I slightly bend the phone the brightness immediately changes. It looks very annoying :(

Does anybody have the same behavior?

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Are you putting your finger in front of the brightness sensor (top-right) or is this just moving the phone around? I agree that it seems to have become quite a bit more "responsive" whereas before it used to be slower

vitaminj ( 2014-12-23 13:09:21 +0200 )edit

@vitaminj, just bend the phone. No any obstacles in front of it. Room with low level of light, single glow lamp. Seems like light sensor became too sensitive.

Valerij ( 2014-12-23 15:00:06 +0200 )edit

Was riding the bus yesterday, and with every street light we passed the brightness went up, then down again. Confusing!

sunnystar ( 2014-12-23 15:33:49 +0200 )edit

I have also saw this behaviour. Sensor indeed seems to be too sensitive. Would be great to have a way to change that sensitivity via terminal (and later on in the settings app?)

Flickta ( 2014-12-23 17:00:39 +0200 )edit

I also recognized that the brightness changes more frequently since the update. And would prefer the lazy behaviour of before too.

Halo2 ( 2014-12-23 18:55:11 +0200 )edit

2 Answers

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answered 2014-12-29 10:18:10 +0200

spiiroin gravatar image

updated 2016-10-11 21:00:18 +0200

Previously adjustments due to ambient light sensor / brightness setting changes were done using constant velocity - which basically meant large changes took looong time to finish and made users feel nothing happened.

Now the transitions are finished in constant time (600 ms) regardless of the magnitude of change -> the device reacts faster which is good or bad depending on user expectations and reason for the change -> the logic probably needs to be revisited, perhaps something like delaying the reaction to sensor change to avoid unnecessary pumping up and down.

Meanwhile the default time value can be adjusted from command line. Using something like 1500 ms should make things much calmer:

  • mcetool --set-brightness-fade-als=1500

(mcetool can be installed via: pkcon install mce-tools)


How it works is that there is optional 9 point median filter with configurable sample time that "eats away" temporary changes / slows reaction to longer lasting changes in light level, followed by either constant time or constant velocity display brightness change.

The 1.x behavior (instant reaction to sensor change in relatively slow 8%/s brightness change) can be activated via:

mcetool --set-als-input-filter=disabled --set-brightness-fade-als=-8

The 2.x default behavior is: ignore short living changes (lasting < 625) ms and then perform the display brightness change within one second:

mcetool --set-als-input-filter=median --set-als-sample-time=125 --set-brightness-fade-als=1000

If that seems too flickery, you can require the change in lightning to last longer before any action is taken, say 2.5 seconds:

mcetool --set-als-sample-time=500

And/or slow down the rate of finishing the brightness level change, say 1.5 seconds:

mcetool -set-brightness-fade-als=1500

Or if you like it really subtle, use both slow to react filtering and low constant velocity change:

mcetool --set-als-sample-time=800 --set-brightness-fade-als=-5
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Looks better. Thank you! Also it would be great if it is possible to restore old behavior in future updates (in settings or in command line).

Valerij ( 2014-12-29 13:07:12 +0200 )edit

Do I need to use root privileges to run this command? pkcon install mce-tools is failing with message "Failed to obtain authentication"

petrikk ( 2014-12-29 14:49:42 +0200 )edit

@petrikk yes, you need root privileges.

rollick ( 2014-12-30 12:16:03 +0200 )edit

Had this behaviour while driving my car on the autobahn. Using HERE maps, other cars "modified" (with their lights) the brightness of my jolla screen very often. This was quite strange. In other situations a fast changing behaviour might be good.

Stephan ( 2014-12-30 20:42:54 +0200 )edit

Filed tasks "Support constant velocity brightness tuning too" and "Try to avoid display brightness pumping due to short-lived ALS changes". Not sure yet about timing of these changes, but will not happen in update11.

spiiroin ( 2014-12-31 09:43:27 +0200 )edit

answered 2015-02-12 11:33:10 +0200

Tongamillo gravatar image

I've got the Jolla Phone now for couple of days. so i can't tell how it was before the update came.

Today i was sitting in a unlit bus outside it was still Dark, playing around with my Jolla but I was nearly trowing up because the Jolla was changing the screen brightness according the streetlamps! the Sensor was doing what it should but waaaaay to fast! everytime the streetlamp came the screen got dark and after bright again till the next streetlamp came.

maybe there should be a delay of 1sec. or an averaging of the signal over 1 or 2 sec. and adjusting according to that? i had now couple of different Mobile phones but that is the worst of all.

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Asked: 2014-12-23 12:41:13 +0200

Seen: 1,000 times

Last updated: Oct 11 '16