GSoC: automatic brightness adjustment

Dario Freddi drf54321 at
Thu Apr 5 12:20:43 BST 2012

Il 05 aprile 2012 07:32, Mike Dean <miketdean at> ha scritto:
> As an electrical engineer, I find this idea sound.

Allow me, as an information engineer and a computer scientist, to
think you missed part of the picture :)
I don't want to challenge your argument of the power consumption of
the webcam even though I'd like to have some numbers (remember the
webcam needs power). But:

* A webcam is not a sampling device as you intend it from a power
consumption pov, and does not work as such. It draws power even when
activated and not sampling, arguably the same amount. If you choose to
turn it up and down, see below.
* Your situation clashes with what could be the driver's capability
* And with HW capabilities, as Sebastian said.
* The overhead of bringing up/down the camera, which is quite
important both from a power consumption and usability point of view,
like Sebastian already said, defeats the benefit
* The device will be still held busy when other apps could need it, no
matter the sample rate and no matter the turn on/off. There will
always be clashes.
* The fact that, by consequence, this feature would not work whenever
you are videocalling.
* And most of all, the fact that the hardware device is neither meant
or designed for this purpose.

I think in the end I don't want this feature in, ESPECIALLY since we
don't even support proper light sensors. And I think that while the
concept might seem appealing, a real-world implementation would be
much worse than you imagine. There's a reason why people build webcams
AND light sensors, after all.

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