Gadgetopia

C'mon Deane. Simple google search yielded this as the first entry:

http://clarkvision.com/imagedetail/eye-resolution.html

Goes into some nice detail about not only the resolution, but things like frame rate and light sensitivity as compared to cameras.

A brief excerpt:

Based on the above data for the resolution of the human eye, let's try a "small" example first. Consider a view in front of you that is 90 degrees by 90 degrees, like looking through an open window at a scene. The number of pixels would be 90 degrees * 60 arc-minutes/degree * 1/0.3 * 90 * 60 * 1/0.3 = 324,000,000 pixels (324 megapixels).

At any one moment, you actually do not perceive that many pixels, but your eye moves around the scene to see all the detail you want. But the human eye really sees a larger field of view, close to 180 degrees. Let's be conservative and use 120 degrees for the field of view.

Then we would see 120 * 120 * 60 * 60 / (0.3 * 0.3) = 576 megapixels.

The full angle of human vision would require even more megapixels. This kind of image detail requires A large format camera to record.

I think this is like comparing apples to oranges. However it is interesting.

The resolution of an image is highly dependant on the dpi of the output device for which it is intended. For example, some typical numbers for output devices:

monitors ~72dpi magazines ~300dpi billboards ~45dpi

A low resolution image can look outstanding on a monitor but very poor when printed in a magazine. You've all seen the cheesy ads in the back of magazines with the blocky photos right?

You can print an 8x10 photo from a 3.2 Mp camera with good results. We could have easily stopped the development there but people were conditioned to look for the most megapixels they could find on a camera. Ok, the higher megapixel sensors are more forgiving because it allows for poor composition on the front end and more cropping on the back end. But let's be realistic, how many times does the average consumer print 8x10s? It is typically 4x6 these days isn't it?

If we could make a parallel, I think 324 megapixels for the human eye is a bit of a stretch. Using that logic, I could say well I have a 3.2 megapixel camera but I keep moving it around so it is actually much more. You could put a wide angle lens on a 2.0 megapixel camera and capture the same 90 degrees by 90 degrees and if the scene were bright enough you could push the depth of field to near infinity and everything would be in focus at once - the eye can't do that. Apples vs oranges. . .

The Gigapixel Project explored this topic in a lot of detail. This project was an attempt to create a camera with each component approaching or exceeding the maximum possible performance.

Here's the page discussing eye response.

I haven't plowed through this information in a while, but the eye response is characterized by a MTF (Modulation Transfer Function) and a resolution in terms of cycles/mm.

IIRC, the limiting performance factor was the response of the red film layer.

From The Limits of Human Vision Michael F. Deering Sun Microsystems http://www.swift.ac.uk/vision.pdf

This is the conclusion "A model of the perception limits of the human visual system was given, resulting in a maximum estimate of approximately 15 million variable-resolution pixels per eye. Assuming 60 Hz stereo display with a depth complexity of 6, it was estimated a rendering rate of approximately ten billion triangles per second is sufficient to saturate the human visual system."

That Gigapxl camera is a fascinating piece of equipment. The resolution and detail available from that camera are, literally, unmatched by any other camera ever made. It's definitely worth taking some time to browse the image gallery on their site, and to read a little bit about their design and problem solving approach towards creating the camera.

Look at a ruler at arms length, can tell millimeters apart easily but below that its difficult, so roughly the lateral spatial resolution is about 0.1 mm.

Applying to the Rayleigh Criterium, an eye with a 3mm pupil should resolve 2.2mm 10m away. The Dawes Limit puts this at 1.9mm. This probably applies to point sources, but definitely not for normal viewing. Experiments show that the eye can comfortably achieve such resolutions being 3m away from the object. That's 70% less than "advertised". Check it out for yourself!