ELI5 : Why do phones and tablets power on and off with full 100 % brightness regardless of the scree brightness settings?

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ELI5 : Why do phones and tablets power on and off with full 100 % brightness regardless of the scree brightness settings?

In: Technology

There needs to be a program running to control the screen brightness for it to be set to some amount.

In those situations, there is no process running for that, as it requires an operating system to run, which isn’t running completely at that time.

There are ways around it but its not really a necessity for the few seconds it takes for the phone to turn on or off.

For two reasons.

When the hardware fires up, it makes sense to perform a function test. I.e, run it at full capacity for a while and monitor that it appears to work.

And…the program that tells the screen hardware what brightness is preferred, that program is not up and running until the entire operating system is done booting up.

So. Those two in combination. It does that because it has been told no different. And it also makes sense to let it, because you can have a quick look at how it behaves to spot issues.

You mean when the device is first booting up?

This is because the sensor that detects ambient light has not been initialized. Once the ambient light sensor is initialized, and the OS has loaded the screen control functions, then it can regulate the screen brightness. Until that happens, the hardware will use the default 100% brightness setting.