How many megapixels is my eye?

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Offline Steve

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How many megapixels is my eye?
« on: 08/07/2011 03:01:02 »
Steve Elliott (on my iPhone)  asked the Naked Scientists:
   Has there been any definitive research into the actual and interpolated resolution of the human eye?

I seem to recall reading somewhere that if you could take a snapshot of what the eyes see, the resolution would be less than my digital camera's 12Mpixels, but because our eyes are always moving, the brain interpolates to make a much higher effective resolution - that's why the photos I take of beautiful sunsets never look quite as good and detailed as what I see!

So, what is the actual resolution of an eye, of both eyes together (which I assume would be slightly higher than one eye because of the stereo views), and the effective in-brain resolution?


Stephen
What do you think?
« Last Edit: 08/07/2011 03:01:02 by _system »

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Offline granpa

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How many megapixels is my eye?
« Reply #1 on: 07/07/2011 18:06:31 »
in theory about 100 million pixels but the image is compressed and sent over 1 million axons to teh brain.

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Offline CliffordK

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How many megapixels is my eye?
« Reply #2 on: 07/07/2011 19:12:02 »
A megapixel is a million "dots", although cameras consider the pixel as containing the 3 primary colors.

According to this...
http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html

There are about 120 million black and white rods in your eye.
And about 6 or 7 million cones (which are divided into 64% red, 32% green, 2% blue).

So, your eyes have the sensitivity of about 120 megapixels in black & white, but less than 5 megapixels in color.

Your brain does an extraordinary job to take this information and create a unified image of your surroundings.

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Offline techmind

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How many megapixels is my eye?
« Reply #3 on: 19/07/2011 23:26:51 »
We've done this question before. A search ought to find it.
The eye has high resolution in the central couple of degrees of vision, and progressively less resolution further off-axis. The brain moves the eye around following details and interesting features which probably gives the illusion of high resolution over a greater field of view. The resolution of the eye is normally specified as and angular resolution, but as a ballpark figure this translates to about 300dpi at a reading distance of about 14 inches.

You can do a quick rough estimate by printing a piece of paper with alternate black and white lines on a laser printer (suggest about 1mm pitch), pin it up outside somewhere (for the best answer, do in good daylight), and step backwards until you can no-longer resolve the lines properly and they go shimmery. Measuring the ratio of the pitch of the lines to the paper-eye distance will give you an approximate answer to the angular resolution of the eye.
"It has been said that the primary function of schools is to impart enough facts to make children stop asking questions. Some, with whom the schools do not succeed, become scientists." - Schmidt-Nielsen "Memoirs of a curious scientist"