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Re: Next step for DAP Ambient Light Events

From: Marcos Caceres <w3c@marcosc.com>
Date: Tue, 28 Aug 2012 02:55:24 +0100
To: Doug Turner <dougt@mozilla.com>
Cc: "Tab Atkins Jr." <jackalmage@gmail.com>, www-style@w3.org, public-device-apis@w3.org, Daniel Glazman <daniel.glazman@disruptive-innovations.com>, Dzung D Tran <dzung.d.tran@intel.com>
Message-ID: <00D45EE85A024442A92D027A1895531E@marcosc.com>



On Monday, 27 August 2012 at 22:00, Doug Turner wrote:

> I am getting different results on the Galaxy Nexus (ICS). Close to double what Tab saw.
>  
> ~380 LUX in the office type lighting.
> ~28000 LUX in very bright light.
>  

  
The following paper by Microsoft might be useful (page 13 contains a table of how Lux values map to different lighting conditions):
http://msdn.microsoft.com/en-us/library/windows/hardware/gg463478.aspx

Though I don't think the paper above cites any sources. I also had little luck in google scholar trying to find a scientific study (though I might just have been looking for the wrong terms)… other sources that present similar tables I found:
http://en.wikipedia.org/wiki/Lux
http://www.engineeringtoolbox.com/light-level-rooms-d_708.html

The wikipedia article actually cites sources, but I've not checked their validity in any detail.  
   
Hope that helps!

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> ----- Original Message -----
> From: "Tab Atkins Jr." <jackalmage@gmail.com (mailto:jackalmage@gmail.com)>
> To: "Dzung D Tran" <dzung.d.tran@intel.com (mailto:dzung.d.tran@intel.com)>
> Cc: "Doug Turner" <dougt@mozilla.com (mailto:dougt@mozilla.com)>, www-style@w3.org (mailto:www-style@w3.org), public-device-apis@w3.org (mailto:public-device-apis@w3.org), "Daniel Glazman" <daniel.glazman@disruptive-innovations.com (mailto:daniel.glazman@disruptive-innovations.com)>
> Sent: Monday, August 27, 2012 11:20:27 AM
> Subject: Re: Next step for DAP Ambient Light Events
>  
> On Mon, Aug 27, 2012 at 10:59 AM, Tran, Dzung D <dzung.d.tran@intel.com (mailto:dzung.d.tran@intel.com)> wrote:
> > A quick un-scientific test:
> >  
> > Nexus 7 tablet (JB) Galaxy Nexus Phone (ICS) Xolo Phone (ICS)
> >  
> > Office lighting: ~550 lux ~170 ~700
> >  
> > Flash light (1"): ~40,000 ~12000 ~48,000
>  
> Interesting. I'd like to see a few more results, to see if the Galaxy
> Nexus is just an outlier, or if things are generally that spread out.
>  
> If they turn out to be that spread out, though, then I recommend
> defining the named light levels not in absolute lux values, but
> instead just defining them generally and noting that devices should
> map their lux ranges as appropriate (with a note that this lack of
> definition is due to the significant divergence in detected lux across
> devices).
>  
> ~TJ  
Received on Tuesday, 28 August 2012 01:55:57 GMT

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