Questions tagged [vision]

Physical processes involved when seeing, and comparisons between with other light detection systems. Includes questions about the eye, optical nerve, brain, corrective lenses, etc.

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37 views

Focus at infinity

I have myopia so I wear corrective lenses. One set of glasses I have is designed to focus from about 2 feet to infinity. I can see the dashboard of a car, but I can also see buildings at long ...
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1answer
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Third Eye and how the brain would see the world [closed]

Let's suppose that through engineering, a third bionic eye would be attached to a human and interfaced directly with the brain. Let's assume this third eye is positioned in the middle of the forehead. ...
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5answers
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How can we see objects with the help of light if we cannot see atoms?

We know that the objects are made up of atoms. We also know that we cannot see atoms with the help of light as the wavelength of light is too big in comparison to atom. So, my question is then: how ...
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0answers
45 views

How do we see things? [duplicate]

What I mean is, suppose white light falls on a red object and is reflected, so when we see the reflected light reaches our eyes we see it as red (probably because its wavelength corresponds to red). ...
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1answer
56 views

Why did a green light appear white when looked out of the corner of my eye? [closed]

The other day I saw a green light emitted from some source far away, and I realised that if I looked at it out of the corner of my eye I perceived it completely white. What is the explanation for this?...
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1answer
30 views

Why the color of light observed dark (almost no light) from section of overlapping of two different colored plastic sheets?

Two transparent plastic sheets say of red and blue color overlap as shown in figure . An observer looks at a clear sky through the sheets. He will observe light coming through sections as, SECTION 1: ...
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2answers
38 views

Why do we only see VIBGYOR colours from dispersion?

I read all the suggested duplicates and they seem to be addressing the relation between primary colours and VIBGYOR. But my straightforward question is when so many colours with different wavelengths ...
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1answer
45 views

Why is desaturated orange = brown, but desaturated blue is just plain blue? [duplicate]

As per wikipedia, "brown" refers to long wavelength hues, yellow, orange, or red, in combination with low luminance or saturation. So what about the short wavelength hues? Is there any ...
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1answer
45 views

Vision: eyes vs cameras

I think this is related to physics, and light waves. Is there some materials that can be seen by human eyes and can't be seen by cameras? (Imagine a special writing) Is that even possible therotically?...
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1answer
64 views

If monochromatic light shines into our eyes, will that activate multiple types of cones or only one type of cone?

I have read this question: Explanation about black color, and hence color where John Rennie says: For example suppose you're looking at red light. Only the "red" cones will generate a signal and ...
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1answer
32 views

How does nearsightedness know what's near versus far?

If I wear a VR headset, I still have to wear my glasses, because the image arriving on the surface of my eye is still arriving as if it were actually far away. But how does that work? Why does the ...
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11answers
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Are colors grounded in physics or are they a matter of human perception? [duplicate]

My father was colorblind, and I always wondered if colors were a matter of physics or if different colors are just a human way of describing and differentiating our visual perception of the world? ...
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1answer
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Which materials are white due to diffuse reflection, and which due to absorption/re-emission of all wavelengths?

Is there any way of knowing which white objects or materials are white due to emission of most or all wavelengths, and which due to diffuse reflection? If there is one type of material I would like ...
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10answers
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What determines whether colors you can't see are visible or not?

So, when someone is red-green colorblind, the colors appear the same to them, like this: And if you're totally colorblind, then things presumably just appear like they would in a black-and-white ...
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1answer
44 views

Can a person with healthy eye see things clearly if he/she uses spectacles?

Let's first see the mechanism of working of concave lens for correction of myopia. If a myopic eye has a near point less than infinity say 1 meter(m) then we use a concave lens of focal length 1, so ...
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Why do some kind of black bands or lines appear when I'm just about to touch two fingers ?There is a second question too [duplicate]

I don't know if I can explain this well. The effect is best visible when you keep your hand in front of a light source. When I'm almost about to touch any 2 fingers (assume between your thumb and ...
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2answers
82 views

What kind of information does light carry so that brain can “see” shapes and distances of objects? [duplicate]

I know that we actually see with our brain in a way that eyes only absorb the incident light upon them and they transform some sort of information to the brain and the actual "seeing" is done by the ...
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1answer
57 views

If we had a good enough eyesight would we be able to see atoms and the fuzziness of the quantum world?

If our eyes had enough precision and calibration to see hundreds of thousands smaller scales than we do, surely our brains would also need a major tuneup to process it. But could our classical body ...
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1answer
38 views

Why my myopia spectacles doesn't allow a person with normal eye to see clearly?

I am a student of class 10. I have been taught that myopia spectacles (concave lenses) corrects the vision by forming a virtual object at the person's far point. But I am unable to figure out one ...
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7answers
6k views

Would visible light still be in a separate classification if we saw “colors” in a different wavelength? [duplicate]

Basically im asking if there's anything special about visible light other than the fact that we use it to see colors. If we saw in another wavelength, would it still be possible to see colors like we ...
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1answer
50 views

Astigmatism and focusing a camera

A thought experiment: assume I have poor eyesight, but using a viewfinder or an LCD screen I was able to focus a camera on an object or landscape with what seemed to me perfect clarity. I took the ...
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2answers
66 views

Why is human eye dynamic range expressed in terms of luminance?

I am learning about photometry to do Physically Based Rendering. As I checked the human eye dynamic range, I was surprised to see it was expressed in terms of luminance ($\mathrm{cd}/\mathrm{m}^2$) : ...
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2answers
55 views

How can a contact lens on the eye's cornea produce a resolved image at the retina?

I'm going to take Wired.com's The Display of the Future Might Be in Your Contact Lens at face value and assume that the concept is legitimate (see also BBC and additional technical details in CNET). ...
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1answer
93 views

Human colour perception – summary needed

I am a graphic designer and I really want to have knowledge about human colour perception but the longer I am looking for and the more I read the harder this topic seems to be. Physics is not my ...
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2answers
82 views

Why don't we see the violet in the rainbow as blue?

I understand that we perceive the sky as blue and not violet because (1) sunlight has more blue than violet in it (see here), and (2) our eyes are more sensitive to blue than to violet. However, I ...
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2answers
47 views

How does human eye perceive distances? [duplicate]

In case of myopia a parallel beam of light appears to come from the far point of the eye when we use corrective concave lenses. But we do not perceive it as it is coming from the far point, instead we ...
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1answer
52 views

Why does the image lose its clarity when it is formed in front of the retina?

This idea is not intuitive to me. How can the formation of image in front of or behind the retina be not clear? Why does the converging point of the rays of light produces a sharp image? Is it ...
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1answer
284 views

Why is the maximum power of accomodation of human eye about 4 D?

I visited some websites and they state that it is because the least distance of distinct vision is $25\,\mathrm{cm}$. However, we know that the diameter of the eyeball is $2.3\,\mathrm{cm}$, so $v=2....
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1answer
145 views

Why do things look bigger when you're far away?

When I'm on my bed looking outside the window, the trees in the park which is quite some meters away looks big and closer than the actual distance. But when I get up from my bed and go and see it ...
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2answers
44 views

Observable detail and wavelength of light needed to observe - How they are connected?

"If we use light to look at the structure of an object, we need to have its wavelength smaller than the size of the details we wish to look at". I read this statement in an answer at Physics ...
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1answer
75 views

Spectral sensitivity of the human eye -

Following the question: Sensitivity of eye I would like to make sure what these % says about? Is it the ability to colour detection? The similar stuff is here: http://www.giangrandi.ch/optics/eye/...
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1answer
102 views

How does a yellow colour filter work in the sense of RGB colour model?

I learnt after reading How do color filters placed in front of a light source,change the color of light that passes through? colour filter work by permitting only one colour and absorbing or ...
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1answer
87 views

Quantum mechanical reasoning to seeing colours

I don't know if I am writing but this is how I understand it: If I am looking at blue paint... White light falls onto the paint, the electron in the atoms of the paint absorbs all white light and ...
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3answers
71 views

A single eye vision vs normal vision [closed]

I am trying to understand the basics of human vision and looking for a model to see pros and cons of a single eye vision vs two eyes vision. Generally my interest relates to a basic project in a ...
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3answers
72 views

Wouldn’t a truly yellow object appear black in a picture?

If I have a truly yellow object, one that reflects only the light with wavelength between 570-590 nm, and photograph it with a camera that detects only RGB to put it together as a color image, would ...
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0answers
28 views

Wavelength absorbed by cornea but not by air

I'm interested in mounting laser diodes on servos and using them to transmit data. However, I'd rather not accidentally blind someone, even if they (say) stare for five minutes into the beam. My ...
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4answers
125 views

Why do we see black objects if they absorb all frequencies?

Black object absorb all frequencies, yet maybe some light is reflected anyway, but why do we see pitch black?
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2answers
46 views

How can the sky be blue and transparent at the same time, from below and above?

The sky is blue, when looking from below. That's based on scattering, no problem with that: Why is the sky blue? But it is also colorless transparent from above. No problem with that either, we look ...
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1answer
32 views

Seeming darkness inside at dusk/dawn with lamps

My question is about a fairly common phenomenon related to light and vision. When you are inside a room with lamps inside that also has windows, your capacity to see well can depend on both the light ...
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3answers
370 views

Effect of layout on text visibility [closed]

My college recently switched to whiteboards. Though writing on a whiteboard with a black ink sounds similar to the conventional way of writing with white chalk on a blackboard, it feels very different....
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3answers
96 views

Can you guess the approximate size in mm of Snellen/vision chart letter? [closed]

I searched a lot but nobody is telling the size of letters of 6x6 vision. Basically, I need to create a rough sketch of any letter of a 6x6 row in Snellen chart. Some sites say it is 8.7 mm from 6 ...
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1answer
27 views

What information can our eye-cones actually extract from a spectrum of illumination?

If I understand correctly, the cones in the human eye work as follows: the three types have a degree of sensitivity for each wavelength. A cone is activated in a one-dimensional "degree of activation",...
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Will myopic vision be improved while diving?

Why does my myopic vision improve under water while wearing a diving mask, compared to my normal vision on land?
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22 views

How large will my buddy's eyes appear underwater while wearing goggles?

My buddy and I are underwater scuba diving. We are both wearing diving masks. I know an object in the water will appear 1.33 times larger. But how large will my buddy's eyes appear inside of his ...
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0answers
42 views

Could this work as a way to make 2D appear 3D? [closed]

So there is an effect where if you close one eye while watching a 2D movie, it appears slightly more 3D. This being because your depth perception no longer has the cue from two eyes. (As an ...
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1answer
40 views

On seeing and especially in the dark

Our retina detects the change in the electromagnetic field due to the jiggling of the atoms surrounding us as I understand the seeing process. In the total absence of a light "source", however, why ...
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2answers
38 views

Is their a way to protect screens from being recorded? [closed]

This idea might sound stupid but... Is there a way a screen would be impossible to record using a prism? I’m not talking recorded by a software but recorded from a camera… If you put a prism layer in ...
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1answer
36 views

Vision bluriness

I don’t know much about vision so I hope one of you guys could clarify me… When people who have vision problems look at an object without their glasses, they’ll see this object with a certain level ...
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0answers
22 views

Reverse engineering visible color spectrum with night vision glasses

Here's the context from a discussion I was having with a friend. Let's say I have a picture on my phone. Would it be possible to watch this picture on my phone with night vision glasses who usually ...
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1answer
49 views

How does the eye see a real image?

If we look at a convex mirror diagram, it produces a real inverted image at the bottom. Let's say a person's eye is above the object. How do the reflected rays reach the eye? since it's a concave ...

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