Human Eye Resolution

Use slide-control to select distance between an observer and an object (like artwork, tv screen, printed material). The purple & teal boxes display maximum resolving power within various parts of the eye. For example, when viewing something 18-inches away in bright sun, the human eye can barely discern 400ppi or details the size of 1/400-of-an-inch (0.0025") under ideal conditions and contrast. The first purple box (cones in foveola), is the highest resolution part of the eye and is the only figure needed for most print/design applications.

Viewing Distance

Smallest Perceivable Spec

Ambient Light

Cone Resolution
(sharp detail & colour)

Rod Resolution
(low light & motion)

none

1° Foveola area can discern fine detail

4° Fovea area can read text

30° Macula area can recognize shapes

60° area can determine colours

120° Peripheral area can detect motion

An example involving HDTV
Multiply the diagonal screen size (in inches) by 49% (0.49), then use the television's resolution like 720, 1080, 2160(4K), 4320(8K), and divide that by the first number. For example, if you have a 60" Ultra-HD (4K) TV, you would take 60 x 0.49 = 29.4, then the lines of resolution (2160) divided by that... 2160 ÷ 29.4 = 73.46ppi (pixels-per-inch on the TV's screen). Next, set the above slide-control to the distance between your television and seating area to see how many ppi are perceivable. In our example, at 8-feet away (or less) your retinas are getting every dot, and at 16½-feet away a 60" 4K and a standard 1080P will appear the same (resolution-wise).