The resolution of the human eye is estimated to be about 575 megapixels, while the highest digital camera resolution is only about 20 megapixels. Image resolution is generally measured in pixels, or the number of dots it contains, with one million pixels to a megapixel. Therefore, the human eye can theoretically see images with more than 28 times more clarity than the highest-quality digital camera. Scientists believe that human eyes are able to see more pixels simply because there are two eyes to intake more pixels for the brain to process. Also, eyes can quickly move around to view more pixels and send the image signals to the brain.
More about the human eye:
Thanks for the great questions (and equally great answers). I have been wondering about this resolution issue of the eye.
Just wondering: What is the resolution of silver halide coating in photographic films? How would their ISO/ASA rating affect their 'pixel' resolution, whatever it may be?