When taking pictures with a digital camera, it's easy to be disappointed in the results. I look at a scene, and see one thing, then I look at the photo, and I see something very different. This isn't surprising, because the human eye is equivalent to a 576-megapixel camera.
The average human retina has five million cone receptors on it. Since the cones are responsible for colour vision, you might suppose that this equates to a five megapixel equivalant for the human eye.
Our eyes have a hundred million rods that detect monochrome contrast. In good light, you can distinguish two fine lines if they are seperate by at least 0.6 arc-minutes (0.01.Degrees).
This gives an equivilant pixel size of 0.3 arc-minutes. If you take a conservative 120 degrees as your horizontal field of view and 60 degrees in the vertical plane, this translates to ...
576 megapixels of available image data.
So The human eye has around 576 megapixels, compared to Nokia Lumia 1020 that has (only) an 41-megapixel camera.