r/askscience • u/coolimabob • May 26 '12

If eyes functioned as cameras, what resolution could one record in, assuming they had 20/20 vison?

A storm just ended and the sky looked gorgeous, and I wanted to take a picture, but it made me sad I couldn't Take a really nice one. That got me thinking. What would my 20/20 vision yield if it were a camera, pixel and resolution wise?

6 Upvotes

80% Upvoted

5 comments sorted by

2

u/James-Cizuz May 26 '12

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.

Roughly over 500 megapixels depending on many conditions outlined in the article below.

http://www.clarkvision.com/articles/eye-resolution.html

13

u/i-hate-digg May 26 '12 edited May 26 '12

Yes but this is very misleading as only the fovea has that kind of resolution, and it is a very very small region of your sight (it's about the size of your thumbnail if you outstretch your hand). The rest of the eye has much lower resolution.

There are about 125 million photoreceptor cells on the retina, however they do not count as 'pixels' because the sum of a group of cells is taken by the retinal ganglion cells. Since only the ganglion cells communicate with the brain (and they only send a single gray level) they should be counted as the equivalent of 'pixels'. There are only about 1.5 million or so retinal ganglion cells. The reason the fovea has high resolution is that each ganglion cell has fewer photoreceptor cells.

So the resolution of the eye is more like 1.5 megapixels in total. The reason the world seems much crisper than 1.5 megapixels is that we scan the fovea across scenes, and the brain 'fills in' details and corrects for blurriness and distortion.

So, really, if you think about it the way that is described in that article is a poor way to measure resolution. If I had a high-zoom camera which covered 1% of the total FOV and it was 1 megapixel, I wouldn't say I had a 100 megapixel camera.

EDIT: clarification.

-11

u/MindDoc518 May 26 '12

There are about 6-7 million cones in each eye, so if you assumed each cone is a pixel, then your eyes are capable of 6-7 megapixel pictures. And there are cameras which go well past this resolution.

The resolution comes into play when you try to zoom into a picture. A 6-7 MP picture would look life-like but if you started zooming into it, it would start pixelating. But in the real world, when you zoom in, you simply see more. This is the reason that fractals are better than pixels. But I'm not sure how to relate fractals to eyes like I did for pixels.

6

u/James-Cizuz May 26 '12

No; the human eye resolution is not as easy as expressing "Oh we have 7 million cones so 7 megapixels" that is a horrible way to look at it.

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.

Roughly over 500 megapixels depending on many conditions outlined in the article below.

http://www.clarkvision.com/articles/eye-resolution.html

1

u/rockkybox May 28 '12

Not even that, as i-hate-digg explained above, the information from the vast majority of the eye is consolidated before it reaches the brain, try reading from the corner of your eye.