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Retina display supportRetina display supportPosted Jan 9, 2013 16:08 UTC (Wed) by niner (subscriber, #26151)In reply to: Retina display support by roc Parent article: Firefox 18 is now available
Actually the behaviour seems not to be consitent with the spec. To quote the spec:
"For a CSS device, these dimensions are either anchored (i) by relating the physical units to their physical measurements, or (ii) by relating the pixel unit to the reference pixel. For print media and similar high-resolution devices, the anchor unit should be one of the standard physical units (inches, centimeters, etc). For lower-resolution devices, and devices with unusual viewing distances, it is recommended instead that the anchor unit be the pixel unit."
So for example a 3rd generation Apple iPad with so called "Retina display" has a screen resolution of 263.92 PPI which is much closer to a 300 DPI print than to the usual 90 DPI of a computer screen. Google Nexus 10 features 300.24 PPI. So I would say these devices are what the spec call "print media and similiar high-resolution devices" and 1px sould be 0.75pt or 0.26458333mm.
Using 2x2 device pixels seems to be just as wrong as using 1x1. 2 display pixels on the Nexus 10 for example are just 0.1692mm wide compared to ~ 0.26mm width of the reference pixel the CSS spec uses.
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Retina display support Posted Jan 9, 2013 21:39 UTC (Wed) by butlerm (subscriber, #13312) [Link]
96 CSS pixels per inch is normal (or at least nominal) for a desktop computer screen. A handheld device is typically going to have a substantially different viewing distance, and as a consequence it isn't at all natural to display the same content at the same number of CSS pixels per inch. A CSS pixel should (roughly) encompass the same angle, not the same physical size.
As a result, 2 x 2 device pixels per CSS pixel is just about ideal for a 192 DPI desktop display. Ideal as in minimizes aliasing for pixel oriented page designs, which are commonplace. If you have a handheld device, the DPI should be higher because the viewing distance is going to be less. 384 or even 400 dpi sounds about right for 2 x 2 scaling (2 dppx) on a device like that. 4x4 scaling someday (~768 DPI handheld, 384 DPI desktop) sounds well within the retina limit to me, at least if you want to avoid eyestrain.
Retina display support Posted Jan 9, 2013 21:45 UTC (Wed) by roc (subscriber, #30627) [Link]
You're not taking into account viewing distance. Tablets and phones are viewed at a shorter distance than desktop displays. For a desktop display viewed at arm's length, a CSS pixel should be one device pixel on a 96dpi screen, but for a phone viewed at half that distance, a CSS pixel should be one device pixel on a 192dpi screen (assuming default zoom).
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