According to Apple, the background and foreground colours are set to black. 
Just setting the brightness to 0 would not work. People can still see what is 
on the display if there is much ambient light.

David Chittenden, MSc, MRCAA
Email: [email protected]
Mobile: +64 21 2288 288
Sent from my iPhone

On 10/04/2013, at 17:01, James Mannion <[email protected]> wrote:

> I was under the impression that what it does is set the brightness to
> 0. This would be the simplest implementation as well if this is the
> case. Setting colors the same would take possibly more programming
> considerations. I'm not entirely sure how it works now, but the
> brightness to 0 makes sense and that is what I previously heard it
> does.
> 
> On 4/9/13, Neal Ewers <[email protected]> wrote:
>> Christopher, what you are saying makes sense. The screen must be on in some
>> way in order to use gestures. I know a couple people who have developed
>> apps. I'll run this by them. That doesn't mean they are experts on screen
>> curtain necessarily, but they might know a bit about it. It does no harm to
>> ask.
>> 
>> Thanks for your thoughts.
>> 
>> Neal
>> 
>> -----Original Message-----
>> From: [email protected] [mailto:[email protected]] On Behalf
>> Of Christopher Chaltain
>> Sent: Tuesday, April 09, 2013 7:53 PM
>> To: [email protected]
>> Subject: Re: Screen Curtain a battery saver, but effective?
>> 
>> What you're saying makes sense if the screen is actually turned off when
>> the
>> screen curtain is on and requires less power than when the screen curtain
>> is
>> turned off. I've heard though, that the privacy of the screen curtain is
>> handled by setting the background and the foreground colors to be the same.
>> I don't know how it really works, but if this were the case, you would not
>> see any battery savings. This is different then say my laptop running
>> Ubuntu
>> where I can physically turn the monitor off and no power at all is being
>> sent to the monitor. Given that the screen on the iPhone is also a touch
>> screen, they obviously can't kill all power to it.
>> 
>> I run the screen curtain for privacy purposes. If it saves me battery power
>> then that's great. If people find that running with the screen curtain on
>> saves them some battery power then they should use the screen curtain. As I
>> said, I haven't noticed a big difference myself, but I go ahead and run
>> with
>> the screen curtain on anyway.
>> 
>> On 04/09/2013 06:11 PM, Victor Gouveia wrote:
>>> While not having done as much extensive research as Neil, grin, my
>>> brother, who is sighted, says that the screen curtain effectively
>>> shuts off the display, while still making it sensitive to touch, so,
>>> the less amount of light being emitted by the cell phone only stands
>>> to reason that it would save battery life.
>>> Having said that, it's been my experience that my battery drops more
>>> quickly when my screen curtain is off doing the exact same thing, as
>>> when the screen curtain is on, so I guess in this respect, the
>>> research I did was experiential.  Smiles.
>>> One can even take this a bit further using a laptop as an effective
>>> means of understanding the concept.
>>> If one puts a laptop side to side with a screen-less note taker, one
>>> finds that the note taker uses up it's battery life a great deal
>>> longer than the laptop.  Even if using a laptop compared to a netbook,
>>> especially those utilizing a solid state hard drive, the smaller
>>> screen means less in the way of power needed to form the picture on
>>> the screen, especially comparing the 17 inch screen laptop to the
>>> minute 7 to 11 inch netbook screens.
>>> In conclusion, the less power you need to run something, the more
>>> battery life you'll save.  At least that's been my experience.
>>> Victor Gouveia
>>> Vice-President
>>> Training Coordinator
>>> VIP Tech
>>> Tel: 1-(888)-737-1115
>>> Fax: 1-(888)-737-1116
>>> [email protected] <mailto:[email protected]>
>>> [email protected] <mailto:[email protected]>
>>> Limiting Disabilities with Limitless Possibilities
>>> 
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>> 
>> --
>> Christopher (CJ)
>> chaltain at Gmail
>> 
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