Auto backlight management?

Bert Freudenberg bert at
Fri Apr 25 05:05:10 EDT 2008

On 25.04.2008, at 10:46, Martin Dengler wrote:

> On Fri, Apr 25, 2008 at 12:07:12AM -0400, Eben Eliason wrote:
>> On Thu, Apr 24, 2008 at 10:43 PM, John Watlington <wad at>  
>> wrote:
>>> Bert misread the spec.  When the backlight is switched off, the  
>>> screen
>>> automatically switches to B&W mode.   Why would you want to take
>>> that out of the control of the user ?
>> It's clear to me that it would be quite useful to have a
>> bright backlight AND black & white mode for reading a book at night,
>> for instance, and this isn't possible in the current UI.
> The camera could be checked once when the device went into/out of  
> ebook mode
> and the backlight changed appropriately.

Malicious software also could snap a picture of the user at that  
moment. This is the privacy issue that Ivan mentioned, and I agree, we  
cannot use a camera image for this.

What I suggested before, but which was not practicable, would be some  
"passive" readout-hardware in the camera that only reports a single  
brightness value. But I was told the current design would require to  
power the camera on for that. And in a new hardware design it may be  
cheaper and better to add a photo sensor than this.

The biggest benefit I see from adding this is power savings. The  
backlight should be automatically turned off when there is enough  
ambient light, to save power. Switching it back on could easily be  
done by the user (or automatically for convenience).

- Bert -

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