# How many Pixels in 20/20 Vision?

Okay, forget depth perception for one minute (pretend you have only one eye if you must), but with all the jargon surrounding video cameras, scanners, HDTV, etc. - where does human vision rate? How many lines of resolution (400, 600, 1 million) before I cannot tell the difference between a “picture” and reality? Sure, a number of factors play a part in video, frames per second for example, which allows me to gauge whether “movement” is real or not, but a still photo is different.

Will this “resolution” idea eventually become something akin to sunblock (SPF 45, 56, etc) where the added benefit of higher quality is so minute as to be imperceptable?

There is no resolution for our analog sight. What we see is simply light bouncing off of the objects around us. There really is no comparison to the way we see things in real life and the way we see things on a computer monitor.

Well, there might be, but I bet it’s a pain actually counting all thoses rods and cones.

The human eye is 60 fps. 20/20 dude, means 20 millimeters high. Focal range is 50 mm I think, hey all this is already on the net or in your library, what am I doing answering it?

handy, the term “20/20” is not a specific measurement, and doesn’t say anything about resolution on the retina. It’s a relative measure of how well someone can see, and thus depends mostly on focusing ability.

If you have 20/20 vision, then your eyes are considered “normal” and you don’t need glasses. But if you have 20/100 vision, then you can’t see very well; what an average person could read from 100 feet or less, you can only read at 20 feet or less.
Anyway, on to the OP.

I did some research on the web, and found this very useful link: http://retina.anatomy.upenn.edu/~lance/modelmath/units_space.html

I measured my monitor screen and found it to be about 30 centimeters high. Where it sits on my desk, it is approximately 1 meter from my eyes. Doing the math, I find that the image projected onto my retina will be about 5.1 millimeters high.

The fovea, the most sensitive part of the retina, contains about 500 cones per millimeter. Multiplying it out, we find this corresponds to a monitor resolution around 2550 pixels high. That’s about three times as sharp as the best image from my 1024x768-pixel video card, though I admit it’s not quite cutting edge.