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Human Eye as Image Sensor


robert mcafee
 

The Human Eye as an Image Sensor

MAURIZIO DI PAOLO EMILIO

In human sight, the eyes, brain and optic nerve are all come into play during the image acquisition process. Cameras were built using the human eye as a model in an attempt to replicate its features.

The eye is composed of various parts. The retina is sensitive to light and is formed by photoreceptors for image conversion. Through the retina the image is broken down into electrical packets and conveyed to the optic nerve. Information is received by the brain at high speed, reaching the diencephalon, where it is processed and matched to the individual's previous knowledge.

Our eyes work with our brain to create the image we perceive: the eyes regulate focus (by bending light through the lens in the eyeball) and translate the photons into an electrical impulse to be processed by the brain.

The cornea is just like a camera lens. The pupil and iris represent the diaphragm. The eyelids are the camera shutter and affect the shutter speed. The crystalline lens is the autofocus. The retina is the real sensor whose dimensions can be comparable to a full-frame of 24x36 mm. The retina is composed of a myriad of pixels. Roger N. Clark calculated a possible number of megapixels under ideal conditions, something like 570 Megapixels.

The focal length of the human eye is between 17 and 24 mm. Our angle of view is 130°, which is reduced to 55° to the focus point. Several studies have stated our eye is a lens with an average shutter speed of around 1/100 second (in healthy individuals).We could say the binomial cornea/pupil corresponds to the binomial frontal lens/mobile lens of the camera: the cornea collects the divergent rays of light and conveys them through the pupil.

The human eye is extremely good at handling images when illuminated by strong light, so it becomes insignificant to talk about "noise" as the human brain simply "completes and corrects" possible problems in sight.


 

The eyelids are the camera shutter and affect the shutter speed.
An apt analogy would be that the eyelids are like a combination lens
cap and a lens cloth with a cleaning solution.

...BC


timo@guildwood.net
 

Also, the eye is a motion picture camera, not a still camera.

Timo

On Sep 25, 2020, at 11:47 AM, Bill Costa <@BC3D> wrote:

The eyelids are the camera shutter and affect the shutter speed.
An apt analogy would be that the eyelids are like a combination lens
cap and a lens cloth with a cleaning solution.

...BC





Bill G
 

AND, the SHARP FOV of the eye, in which the rays hit the FOVEA, the ONLY section of the eye which has sharp resolution is a total of 2 deg. of center vision.   If you try to read written text while focusing on one word from 15"+, and stay fixated on that word, and try to read the adjacent word or two, u will see how poor all of our vision is, other than the Foveal 2%.   The fact the eyes focus range is 55 deg is useless, as the resolution is so low to start with, nothing is resolvable.  Our peripheral vision is primarily for sensing movement and the existence of objects.
Video is at 24-60fps, eyelids don't blink at this speed.  The only real useful information was the eyes shutter speed is estimated at 1/1000s.  


On Fri, Sep 25, 2020 at 8:57 AM timo@... <timo@...> wrote:
Also, the eye is a motion picture camera, not a still camera.

Timo

> On Sep 25, 2020, at 11:47 AM, Bill Costa <Bill.Costa@...> wrote:
>
>> The eyelids are the camera shutter and affect the shutter speed.
>
> An apt analogy would be that the eyelids are like a combination lens
> cap and a lens cloth with a cleaning solution.
>
> ...BC
>
>
>
>
>







robert mcafee
 

Article stated shutter speed of human eye of 1/100 sec (0.01) not 1/1000 (0.001). 

On Friday, September 25, 2020, 12:18:51 PM EDT, bglick97@... <bglick97@...> wrote:


AND, the SHARP FOV of the eye, in which the rays hit the FOVEA, the ONLY section of the eye which has sharp resolution is a total of 2 deg. of center vision.   If you try to read written text while focusing on one word from 15"+, and stay fixated on that word, and try to read the adjacent word or two, u will see how poor all of our vision is, other than the Foveal 2%.   The fact the eyes focus range is 55 deg is useless, as the resolution is so low to start with, nothing is resolvable.  Our peripheral vision is primarily for sensing movement and the existence of objects.
Video is at 24-60fps, eyelids don't blink at this speed.  The only real useful information was the eyes shutter speed is estimated at 1/1000s.  

On Fri, Sep 25, 2020 at 8:57 AM timo@... <timo@...> wrote:
Also, the eye is a motion picture camera, not a still camera.

Timo

> On Sep 25, 2020, at 11:47 AM, Bill Costa <Bill.Costa@...> wrote:
>
>> The eyelids are the camera shutter and affect the shutter speed.
>
> An apt analogy would be that the eyelids are like a combination lens
> cap and a lens cloth with a cleaning solution.
>
> ...BC
>
>
>
>
>







 

Bob, thanks for the info that started this thread, but please also give the source of the text when you post content from others, not just the author.

I found a couple of other interesting sites (when trying to find your original reference).
https://www.cambridgeincolour.com/tutorials/cameras-vs-human-eye.htm This also compares the human eye to a camera. I find it odd that such a comparison hardly brings up binocular vision at all, except regarding field of view. But they do slip in this comment: "even though our eyes capture a distorted wide angle image, we reconstruct this to form a 3D mental image that is seemingly distortion-free".

Another article the same site addresses stereoscopic photography but only regarding "animated 3D stereo photography" aka "wobbles" or "wiggles" (many/most of us would agree with calling them "3D wobbles" but would disagree that these are "stereoscopic" per se, as in the title.) 
They did acknowledge other 3D display methods but implied that these were too complicated or specialized for a general photographer to be interested, at least not as a beginner.  I did find it interesting that they suggested taking image pairs intended for this type of display with convergence at a mid-distance rather than parallel, for better rotation around a mid-distance point. -Linda

On Fri, Sep 25, 2020 at 11:44 AM robert mcafee via groups.io <geargod2=yahoo.com@groups.io> wrote:
Article stated shutter speed of human eye of 1/100 sec (0.01) not 1/1000 (0.001). 

On Friday, September 25, 2020, 12:18:51 PM EDT, bglick97@... <bglick97@...> wrote:


AND, the SHARP FOV of the eye, in which the rays hit the FOVEA, the ONLY section of the eye which has sharp resolution is a total of 2 deg. of center vision.   If you try to read written text while focusing on one word from 15"+, and stay fixated on that word, and try to read the adjacent word or two, u will see how poor all of our vision is, other than the Foveal 2%.   The fact the eyes focus range is 55 deg is useless, as the resolution is so low to start with, nothing is resolvable.  Our peripheral vision is primarily for sensing movement and the existence of objects.
Video is at 24-60fps, eyelids don't blink at this speed.  The only real useful information was the eyes shutter speed is estimated at 1/1000s.  

On Fri, Sep 25, 2020 at 8:57 AM timo@... <timo@...> wrote:
Also, the eye is a motion picture camera, not a still camera.

Timo

> On Sep 25, 2020, at 11:47 AM, Bill Costa <Bill.Costa@...> wrote:
>
>> The eyelids are the camera shutter and affect the shutter speed.
>
> An apt analogy would be that the eyelids are like a combination lens
> cap and a lens cloth with a cleaning solution.
>
> ...BC
>
>
>
>
>







robert mcafee
 

Regrettably this was a document in a newsletter without further attribution than the author’s name. Moreover the newsletter was available to subscribers only so not generally accessible

On Saturday, September 26, 2020, 10:05:23 AM EDT, Linda N <ljnygren@...> wrote:


Bob, thanks for the info that started this thread, but please also give the source of the text when you post content from others, not just the author.

I found a couple of other interesting sites (when trying to find your original reference).
https://www.cambridgeincolour.com/tutorials/cameras-vs-human-eye.htm This also compares the human eye to a camera. I find it odd that such a comparison hardly brings up binocular vision at all, except regarding field of view. But they do slip in this comment: "even though our eyes capture a distorted wide angle image, we reconstruct this to form a 3D mental image that is seemingly distortion-free".

Another article the same site addresses stereoscopic photography but only regarding "animated 3D stereo photography" aka "wobbles" or "wiggles" (many/most of us would agree with calling them "3D wobbles" but would disagree that these are "stereoscopic" per se, as in the title.) 
They did acknowledge other 3D display methods but implied that these were too complicated or specialized for a general photographer to be interested, at least not as a beginner.  I did find it interesting that they suggested taking image pairs intended for this type of display with convergence at a mid-distance rather than parallel, for better rotation around a mid-distance point. -Linda

On Fri, Sep 25, 2020 at 11:44 AM robert mcafee via groups.io <geargod2=yahoo.com@groups.io> wrote:
Article stated shutter speed of human eye of 1/100 sec (0.01) not 1/1000 (0.001). 

On Friday, September 25, 2020, 12:18:51 PM EDT, bglick97@... <bglick97@...> wrote:


AND, the SHARP FOV of the eye, in which the rays hit the FOVEA, the ONLY section of the eye which has sharp resolution is a total of 2 deg. of center vision.   If you try to read written text while focusing on one word from 15"+, and stay fixated on that word, and try to read the adjacent word or two, u will see how poor all of our vision is, other than the Foveal 2%.   The fact the eyes focus range is 55 deg is useless, as the resolution is so low to start with, nothing is resolvable.  Our peripheral vision is primarily for sensing movement and the existence of objects.
Video is at 24-60fps, eyelids don't blink at this speed.  The only real useful information was the eyes shutter speed is estimated at 1/1000s.  

On Fri, Sep 25, 2020 at 8:57 AM timo@... <timo@...> wrote:
Also, the eye is a motion picture camera, not a still camera.

Timo

> On Sep 25, 2020, at 11:47 AM, Bill Costa <Bill.Costa@...> wrote:
>
>> The eyelids are the camera shutter and affect the shutter speed.
>
> An apt analogy would be that the eyelids are like a combination lens
> cap and a lens cloth with a cleaning solution.
>
> ...BC
>
>
>
>
>