One minute of arc pixel
What makes you think a 264 PPI iPad is not a "retina" display ? Remember, the "Retina" marketing is not just about a fixed PPI, but a given PPI for a viewing distance.
Yes,
Steve Jobs at WWDC 2010 talked about a “magic number” of 300 px/in at ”10 or 12 inches”, i.e. 25 to 30 cm. The slides didn’t include that precondition and it is hardly repeated elsewhere.
What’s the typical viewing distance for …?
- small handheld devices like smartphones (iPhone, iPod)
- large handheld devices like tablets (iPad)
- desktop screens (iMac)
- television screens
- hardcover books
- broadsheet newspapers
Except for TVs that should range between 20 cm and 60 cm, usually 30 cm to 40 cm for anything handheld.
If Apple believes you hold the iPad from farther away than your typical smartphone, then 264 PPI could very well fit into the "retina" marketing
That won’t be that easy, because they’ve established the “magic number” 300 and haven’t mentioned viewing distance all that much until now – they could have talked about human physiology, e.g. 1' pixel size, instead, which is an long-established rule of thumb, but no journalist understands that. The CSS reference pixel is about 1.28', by the way, and all but high resolution (96 px/in at arm’s length).
Not surprisingly, 1' at 30 cm is 87 µm/px or 291 px/in, i.e. close to the “magic number”. (10 cm → 873 px/in, 20 cm → 437 px/in, 25 cm → 349 px/in, 40 cm → 218 px/in, 50 cm → 175 px/in, 2.5 m → 35 px/in.)
A 42" 16:9 1080 lines HDTV set has about 52 px/in and would have to be just 1.66 m apart for 1' pixels. A QXGA iPad with current display size would have to be hold at a regular distance of 33 cm for 1' pixels.
At QXGA resolution (264 px/in) the iPad 3 then must have a regular viewing distance of ca. 1.14 times that of the iPhone by Apple’s Retina standards (i.e. 300 px/in at 10in minimum distance), or 1.24 times it if their appearance were to match. That’s a minimum distance anywhere between 28.5 cm and 37 cm.