Both of these statements on Wikipedia have no citation, but are roughly backed up by 6. In this case, under optimal conditions, the limit is about 0.5 arc seconds. This same entry describes The smallest detectable visual angle produced by a single fine dark line against a uniformly illuminated background is also much less than foveal cone size or regular visual acuity. According to 3 the theoretical upper limit of human visual acuity lies somewhere between 20/10 and 20/8 vision.Īccording to 4 hyperacuity can differentiate misaligments as small as 8 arcseconds (450ppd). For example, American baseball star Mark McGwire is widely reported to use contact lenses that improve his 20/500 vision to be better than 20/10 5.ĭistinguising details at 150ppd would require 20/8 vision. However, corrective eyewear can often achieve this level. Anecdotally, my eye doctor told me that in all of his 20+ years in practice he has only seen one person (a teenager) who measured at this level without glasses.
The graph on page 489 of 1 shows that only one or two individuals in the 100+ of tested 17-18 year olds got close to this limit (shown as -0.3 logMAR). Seeing details at 120ppd is equal to "20/10" vision (or "6/3" in Europe). Visual acuity peaks at around 25 years old and then slowly declines, but even then the average 75 year old has better eyesight than 20/20.
While visual acuity changes per person and over time, the average acuity in adults is about 1.6 times better than 20/20, roughly 20/15 vision, or 80ppd. This is defined as the "normal" visual acuity for adults, but it is actually not the average. "20/20" vision (or "6/6" in Europe) corresponds to being able to resolve details 1 arcminute in size, or 60 pixels per degree. limit of high contrast feature detection 4
limit of alignment detection (hyperacuity) 4Īpprox. Visual Density pixels per degree (ppd) at center (~ 123 at edge)Ģ0/10 vision practical upper limit of visual acuityĢ0/8 vision theoretical upper limit of visual acuity 3Ģ0/4 vision approx.The perceived "visual density" of a screen-and thus the amount of anti-aliasing possibly needed to make computer graphics look convincing and smooth-is dependent on the pixel density of the screen (the "ppi") and the distance from the user's eyes.Īdjust values below to calculate the visual density, or select a different value to control and instead enter the desired ppd.
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