Right I dont even know if this is possilbe, but can the resolution of the eyes be measures, i.e like you can get a 10 megapixel camera, i guess eyes would be vastly more powerful than any camera, got any ideas?
Certainly they can. The rods and cones in the retina have finite size, as do the sensor elements in a digitial camera. Provided the lens of the eye isn’t the limiting factor, the graininess of the retina limits resolution. Cones in the fovea are about 1-1.5 microns in diameter and 2-2.5 microns apart. Rods are about 2 microns in diameter. The spacing of detectors is denser in the fovea (near the center of your visual field) and sparser the farther away you get.
Visual Acuity – how good the resolution is – depends upon intensity and other conditions, but normal visual acuity is usually pegged at about one minute of arc.
I swiped all this from the beginning of chapter 5 of Warren Smith’s Modern Optical Engineering.
In addition to the spacing of the actual rods and cones, the neural circuits connected to the rods converge more than those connected to cones - quoting from “Sensation and Perception” by Goldstein, “On the average about 120 rods pool their signals to one ganglion cell, but only about 6 cones send signals to a a single ganglion cell”. Hence, when you are using your rods only (i.e. in low light) you have a lot less resolution than when you are using your cones.
True perceptual resolution is more tricky to calculate though, because our visual system performs all sorts of tricks and dodges; with a conventional camera, for example, if you allow the camera to wobble a bit and interpolate a number of consecutive frames, you can derive more genuine detail than the raw pixel resolution is capable of detecting (NB: I’m not talking about the same kind of single-frame resampling/interpolation used by cheap camera and scanner manufacturers to give their products falsely-impressive specifications)
There’s a professor at MIT who claims the elements of the retina either are or can be witred together in a way to give you hyperresolution (which seems very different from what Canadjun writes). I personally don’t know exactly how it’s wired up, but for practical purposes, things work pretty much as Smith’s book says. I doubt if any of us can wobble our heads and process the result in a Mangetoutian manner to exceede resolution specs. We’re stuck with our eyes as is.
We don’t need to wobble our heads, we merely use ocular tremors
According to Britannica visual acuity under really good light can be as good as 30 sec. of arc and under normal daylight is about 1 minute.
As an illustration of what this means, it is not necessay to print photos ( for viewing at 1 foot or 30 cm under good light) with a resolution of better than about 300 dots/ inch.
The 300 dpi number provided by David Simmons is correct according to publishing “lore,” (which has lots of tradition and experience, but is a little short on the scientific analysis). But that number comes with some caveats.
Generally, 300dpi color is considered photographic to casual observation, but someone who’s trying to see the pixels will still see them. Generally 600-1200 dpi (numbers between those values are rarely used) is assumed to be imperceptible.
The numbers are higher in black and white, especially with fine detail like fonts. Here, you may have to go as high as 2400 dpi for deliberate inspection not to show pixelation artifacts.
(All of these, of course, assume standard viewing distances: a foot or so, and unmagnified).
A film photograph is generally 2500-3500 “dpi”, although of course the “pixels” are of uneven size and shape, and not arranged in a grid, hiding a multitude of sins. Also, this number may be (I can’t find the cite at the moment) for the (small) negative rather than the final printed image. This resolution is almost certainly overkill for the human eye, as shown by the fact that you can “blow up” photos quite a bit before you start losing clarity.
Unfortunately, I don’t think any of this answers the OP’s question, because as Mangetout pointed out, you get frame-to-frame and motion effects as well, so the apparently resolution of the eye will be higher than it’s “static” resolution. I think you’d have to test it; and I’m having trouble figuring out how you could design a test for a “single frame” of the eye and still be able to test detail detection.