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Re: [css3-values][css3-mediaqueries] resolution in dpi / dppx

From: Simon Sapin <simon.sapin@kozea.fr>
Date: Mon, 28 Jan 2013 20:20:09 +0100
Message-ID: <5106CF69.2040304@kozea.fr>
To: François REMY <francois.remy.dev@outlook.com>
CC: "www-style@w3.org" <www-style@w3.org>
Le 28/01/2013 20:00, François REMY a écrit :
>> For instance, if we say the viewing distance is about half an arms
>> length then the size of a reference pixel would be about 1/128
>> physical inches. Given 312 device pixels per physical inch, this
>> gives 312/128 = 2.4375 device pixels per reference pixel.
> Thanks for the clarification. Is there an online calculator that
> gives the optimal size of a pixel (or the DPI) given the viewing
> distance?

The reference pixel is a visual angle (of about 0.0213 degrees) that 
projects to 1/96 inch at a distance of 28 inches. So at a viewing 
distance D, the reference pixel is (1/96) * D / 28 = D/2688.


Of course real devices pick some approximation of that for their actual 
CSS pixels, and the actual viewing distance is often unknown and variable.

Simon Sapin
Received on Monday, 28 January 2013 19:20:33 UTC

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