Naked Science Forum

Life Sciences => Physiology & Medicine => Topic started by: Steve on 08/07/2011 03:01:02

Title: How many megapixels is my eye?
Post by: Steve 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?

Title: How many megapixels is my eye?
Post by: granpa 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.

Title: How many megapixels is my eye?
Post by: CliffordK 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.

Title: How many megapixels is my eye?
Post by: techmind 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.