\n — @adurdin is thinking aloud

So, is single line of black pixels on a white background invisible from 10” on the iPhone 4 display?

@aggroboy

Let’s see. The display on the iPhone 4 is the same height as that on the earlier model iPhones: 76mm. It has 960 rows of pixels. Therefore each pixel is 0.079mm high. With the iPhone held 250mm (10 inches) away from the eyes, each pixel is 2.arctan(0.079/250/2) == 1.1 minute of arc. According to Wikipedia, the naked eye has a resolution of 1 to 2 minutes of arc.

No, a single row of pixels is still clearly visible from 10” on the iPhone 4.

(I could have avoided the trig and just quoted Wikipedia: “Observing a nearby small object without a magnifying glass or a microscope, the usual distance is 20–25 cm. At this close range, 0.05 mm can be seen clearly”, but you know, maths is fun!