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I encountered this concept: device pixel ration, some said it is the ratio between physical pixels and logical pixels.

For example iPhone has:

  • Physical resolution: 960 x 640
  • Logical resolution: 480 x 320

so does it mean that the height of each physical pixel is the screen height/960 ? And the height of each logical pixel is equal to twice the height of the Physical pixel?

Blake
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  • On that post, they say the opposite: http://stackoverflow.com/questions/8785643/what-exactly-is-device-pixel-ratio – user1835565 Jul 31 '14 at 12:13
  • The problem is those pesky new high resolution screens -- or, rather, legacy web pages (and to a lesser extent, applications) that specify positions and sizes in `px` *pixels*. When taken literally, every web page would appear way too small. So Apple invented the "logical pixel" measurement unit, whereas "physical pixels" are the ones you would see. (If only they weren't so darn small.) – Jongware Jul 31 '14 at 12:14
  • @Jongware thanks! How about the `device independent pixels`, is it something similar to logical pixel? – Blake Jul 31 '14 at 12:19
  • @Jongware LOL, I got it from http://msdn.microsoft.com/en-us/library/windows/desktop/ff684173(v=vs.85).aspx , and I still don't quite get it after reading the article... – Blake Jul 31 '14 at 13:02

2 Answers2

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We can say that 4 physical pixels make 1 logical pixel ;-)

In other words: most recent retina displays have much more pixels than original iPhone, but to maintain compatibility and "visual size" software use 4 physical pixel to render a unique logical pixel.

Kennet Celeste
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Luca Detomi
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4

You can take a look at the site below:

http://www.iosres.com

For iPhone 4s logical screen resolution is half of the actual resolution (not include in the site above).

Vas Giatilis
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