If someone has short or long sight, is it possible to tune image on a computer monitor in such way, that a person could see it sharp as if they were wearing glasses? If not, will 3d monitor make it possible?
[Physics] Is it possible to blur an image in such way that a person with sight problems could see it sharp
opticsvision
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You are looking at the outer surface of the eye through the glasses. The eye forms its image on the retina.
If you took a picture of your mother wearing glasses that showed her retina, you could adjust the camera to see the retina in focus. Light from a point on the sensor of your camera would go through both the camera lens, the glasses, and her eye's lens to form a point on her retina. That means light from a point from her retina would follow the same rays backwards and form a point on your sensor.
On the other hand, when you wear her glasses, they cause rays from the camera sensor to come to a focus in front of or behind your retina. Light from that point could follow the rays backward to a point on the sensor, but a point on the retina would be out of focus.
The glasses themselves are usually weak lenses. Usually they have a focal length of a meter or so. Compare that to eye lenses which have (or should have) a focal length of the eye's diameter. Likewise, camera lenses have short focal lengths.
When you focus the camera on a face, light from a point on the face comes to a point on the camera sensor. Light from slightly farther or closer are almost points. The camera uses a small aperture, which blocks rays except those that travel pretty close to a straight line. These rays come to an almost point. This gives the camera some depth of field. A ranges of distances near the true focal plane are close enough to in focus that they look clear.
You can see the effect of an aperture by taking off your glasses and seeing the blurry world. Look through a pinhole and the focus improves. When you get an eye exam, this is why the opthalmologist puts drops in your eye to dilate it. He maximizes your eye's aperture so he can learn about all your eyes defects, not just the central portion.
The weak glass lenses change the angles of rays slightly, as if that portion of your face was a little closer or farther away. But not so much that it is noticeably out of focus, given the camera's depth of field. The eye's lenses is much stronger. The retina would be well out of focus.
Best Answer
Let's take a simple original picture to look at - just two nearby dots on a white background. If you have bad vision, the dots look blurred.
The way good vision works is to ensure that all the light hitting any particular small area of your retina comes from the same direction in front of you. Conversely, all the light coming from one direction hits one specific spot on your retina.
When you have bad vision, the light from a locus of nearby directions all hits on the same part of your retina, and the light from a particular direction is smeared out over an area on your retina. Hence, blurred vision is an averaging effect. When you look at the dots, you'll see them smear out into each other.
You might try to compensate for this by making a "counter-blurred" image where the source dots are smaller, but if the original dots are close enough that light from the center of one dot is spilling over to overlap light from the center of the second dot, making the dots smaller won't fix that problem. Hence, the dots will always appear blurred. You can't create the impression that the original has for someone with good vision.
A photograph is really just a bunch of nearby dots, and so the same problem applies.
I don't know about the 3D monitor, though. I suppose if it can control the direction of light coming off it, it could be modified to focus the light some and create a sharp image for someone with blurred vision.