Illustrating a Conjecture Regarding iPhone Screen Sizes
Update 2014.09.11 // For a post-announcement breakdown, see this fabulously-illustrated post.
I thought I'd jump into the fray of Apple product speculation with an illustration of John Gruber's guess at new iPhone displays. For context, go read his insightful essay, Conjecture Regarding Larger iPhone Displays. Although the essay deals with several different units of measurement—inches, pixels, and points—the main line of reasoning focuses on one:
It’s about points. User interfaces in iOS aren’t specified in display pixels, they’re specified in virtual points.
With the advent of retina-resolution screens, Apple replaced the pixel with the point as its fundamental UI unit of measurement. On Apple's non-retina devices, 1 pixel equals 1 point. Its current generation (@2x) of retina devices has 2 pixels per point, for each dimension. So a 1 x 1 point @2x retina measures 2 x 2 pixels in dimension (4 pixels in area.)
The more points, the more content. Not pixels. (In general. An exception is Final Cut Pro X's video viewer, which matches video to display pixel to pixel.)
My first illustration measures out the iPhones interface in points. According to Gruber's guess, the 5.5" iPhone will have a whopping (for an iPhone) 2208 × 1242 pixels. But this will be @3x retina, where
an @3x point is a 3 × 3 square of 9 pixels.
If he's right, the 5.5" iPhone scales points up by a factor of 1.06, meaning that it takes more physical display area (more square inches) to display the same number of points. So a 100 x 300 UI element on the 4.7" iPhone (@2x retina) would take up 0.61" x 1.84", whereas the same element on the 5.5" iPhone (@3x retina) would take up 0.65" x 1.95".
My second illustration measures out the iPhone interface in inches. You can see that the 5.5" iPhone is disproportionality larger than the other models. This is because of that 1.06 scale factor.
Just to be clear, I'm not saying that the 5.5" model shows less points than the 4.7" model. Just that it doesn't show as much more as it would if it kept the same scale factor. For why the 1.06" scale factor is necessary read Gruber's essay.