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.

Filter by
Sorted by
Tagged with
1 vote
1 answer
30 views

UV & IR radiation are mostly absorbed by water. Our eyes are predominantly water. If our eyes were made of another liquid, could we see slight UV/IR?

Firstly, I'm not a physics guy. I just think it's neat, that's all. I was reading a post on here about why water is transparent (I was more interested in why milk isn't) and saw a graph that showed ...
user avatar
0 votes
1 answer
30 views

How does curvature of our eye affect our perception of the world? [closed]

The front part of the eye which can allow light to enter is a bit curved, so shouldn't this cause us to see a curved distorted version of reality when it is really not there? Is there any way to ...
user avatar
0 votes
0 answers
35 views

Why do eyeglasses use meniscus lenses?

Any eyeglasses prescription could be filled exactly with "symmetrically-shaped" lenses. E.g., a far-sighted person could use a symmetric biconvex lens (i.e., the normal "magnifying ...
user avatar
  • 996
0 votes
0 answers
45 views

How to calculate Distance $D$ to object from a camera with known $H$?

I am using algorithm to draw a bounding box around object when they appear in camera as shown in attached image. The main confusion is that i consider the object closer to camera when the Distance $D$ ...
user avatar
3 votes
2 answers
95 views

Does this work to reduce eyes strain? Enlarge the PC monitor with a lens

I have an idea to reduce eyes strain, but don't know if it works. I work by looking at PC monitor all day long and I believe my myopia condition is getting worse and eyes strain occurs are due to ...
user avatar
  • 172
0 votes
1 answer
45 views

Proofs for off-axis focal lengths of a concave mirror

I am reading "Fundamentals of Optics" the 4th edition, by Francis Jenkins. The book mentions a conclusion for off-axis concave mirrors: That is, depending on: mirror radius of curvature $r$...
user avatar
  • 257
0 votes
2 answers
123 views

Blinking LED and the human eye/perception

When an LED is flashing at 2 times a second, the human eye can perceive the ON and OFF state. We can clearly see when the ON state is and when the OFF state is. When it is flashing 10,000 times per ...
user avatar
0 votes
1 answer
57 views

If a human was moving fast enough how bright would the blue-shifted heat be? Would it be detectable by an average human eye on an average night?

I guess another way to answer this question would be if our eyes had the capability to detect the peak black-body wavelength that is emitted by humans would it be enough radiation to detect if we were ...
user avatar
0 votes
1 answer
30 views

Question about obscura eye lens

Assume I have some contact eye lenses which I covered with black color, so they're not transparent anymore. Then I made a tiny hole at the center of each eye lens. What kind of an image will I see if ...
user avatar
0 votes
1 answer
41 views

Do all objects we see emit light which then forms an image inside our eye?

Daily life we see so many objects .Often in textbooks the ray diagram for the image formation in eye is shown by showing light rays coming from the object and making an image in inner layer of eye . ...
user avatar
  • 485
0 votes
2 answers
42 views

On a fundamental level, why is white balance in cameras even necessary?

When searching online about what the white balance setting in cameras does, you'll probably find an answer that goes something like this: When taking a photo, the color of the lightsource might be ...
user avatar
1 vote
2 answers
78 views

How does transition from violet visible light to invisible ultraviolet look like?

By increasing the frequency of electromagnetic wave in visible range, human eye sees it as a color change. But how human eye will see transition after violet wavelength to ultraviolet? As far as I ...
user avatar
1 vote
0 answers
20 views

Changing the apparent focal distance of an object

I'm not completely confident this is the write SE site to post this on, but it seems like the most relevant one. I want to make an object (with negligible thickness) that is around one to five ...
user avatar
  • 11
2 votes
3 answers
399 views

How do we perceive object distance in refraction/reflection?

Suppose we have some object, from which light rays reflect off and reach our eye. In this example, we can directly see this object, and the image is formed on our retina. However, consider a coin kept ...
user avatar
  • 417
0 votes
1 answer
52 views

How can one calculate the velocity of an object that appears as a blur?

Around how could you estimate the speed of an object which appears as a blur to the human eye? And by blur I mean to the extent it is hard to trace or make out. I looked this up but the best I could ...
user avatar
  • 221
0 votes
0 answers
34 views

How far can the human eye see? [duplicate]

This question has already been asked but the answers are old and the links no longer work. I'm interested in the answer but even more in research papers that have shown the answer.
user avatar
  • 23
0 votes
1 answer
117 views

What is YIQ color model?

As we know that RGB monitors requires separates signals for red, green, and blue components of the image but television monitors uses single composite signals. For this composite signal use YIQ color ...
user avatar
  • 103
2 votes
1 answer
48 views

Why can't we see farther object in mist or fog while we can see closer ones at some rate?

Why can't we see objects farther away in mist or fog but we can see closer objects at some rate? Is that due light can't reach us from farther object to our eyes as they got scattered such a high ...
user avatar
0 votes
3 answers
105 views

What if cameras get better than our eyes?

What happens when camera technology evolves so dramatically that (without considering zooming) camera lenses get “better” than our human eye? Do we see the footage in higher definition, or do we ...
user avatar
2 votes
1 answer
76 views

Red cones spectral sensitivity

Most sources seem to give the spectral sensitivity of cones in the human eye as this: As you can see all three curves have one maximum at a specific frequency. However some sources state that red ...
user avatar
1 vote
2 answers
104 views

Why do the eyes of a person wearing glasses not look blurry if almost everything looks blurry when I wear them?

When I wear my mother's (hyperopic) glasses, almost everything appears blurry, (the reason for which was explained in this answer). What I don't understand, is why this doesn't work backwards. ...
user avatar
  • 2,733
0 votes
2 answers
55 views

Myopia far point virtual image

My textbook says that a diverging lens works by rendering the object a virtual image at the myopic eye’s far point. However, wouldn’t the eye then perceive an object farther than its far point at the ...
user avatar
0 votes
2 answers
70 views

Why i see the golden glow of sunlight on green leaf during evening although an object absorb all the colour and reflect a particular colour light?

Today I notice very weird (for me) phenomenon, I was in open in evening in a garden , and looking at leaves of trees around me. 1.I see a yellowish glow of sunlight on it along with green colour of ...
user avatar
-1 votes
2 answers
75 views

Why we can see cone of white light (not blue) from torch in night but not in day light?

Why we don't see blue colour when we look forward in a open ground, sunrays are there and gases are there. Then why it is not appearing blue like sky but white? Also when I turn on a torch in day ...
user avatar
0 votes
2 answers
85 views

Why can't we see the glow of scattered light which has been scattered very far away?

It said to use red colur objects as a sign of danger because it is scattered at least and hence can be seen from far? But if use suppose blue colour bulb in a open area (where no objects to absorb ...
user avatar
0 votes
1 answer
64 views

Can we see the image of inside of our eye, in front of the eye?

Yesterday, I was sitting with a really bright computer screen (brighter than usual) right in front of me (about 30 cm) and it was like a cubicle (most of the light was blocked from all 3 sides — front,...
user avatar
0 votes
3 answers
101 views

Convex lens in our Eyes

I just learned that our eyes are made up of bi-convex lens, and I know that convex lens are also called converging lens since they converge to form real images that can be caught on a screen. But why ...
user avatar
  • 65
1 vote
1 answer
49 views

Why objects dont appear closer and smaller to a myopic person and far and larger to hypermetropic person after wearing spects?

I am a myopic person, and wear a concave lens. It is taught to us that lens I wear help to form image on my far point and thus help me to see far object. 1.But we have also learn that concave lens ...
user avatar
0 votes
0 answers
19 views

Units of measurement in cone activation?

I have a bit of a specific question. I'm writing my thesis on optics and colour perception and I'm stuck at the formulae regarding cone activations. Cone activations are adimensional values that ...
user avatar
0 votes
1 answer
62 views

How our eye see real images formed by pinhole camera? [duplicate]

How do we(eye) see real image form in pinhole camera? 1.Are rays that are forming image pass through screen and reach our eye help us too see it ? OR Light rays from hole from where we are looking at ...
user avatar
0 votes
1 answer
98 views

Are there an infinite or finite number of colors (can we see infinity?) [closed]

Take any blue or red, mix in equal parts and you have purple. Now mix 50 units of red and add 25 units of blue for another purple, then 50 units of red and 12.5 units of blue for yet another purple ...
user avatar
0 votes
0 answers
103 views

Why are diffraction spikes from bright light sources longer with larger pupil than with smaller?

In photography, it's well known that reducing the aperture leads to the starburst effect, like in the following photo: (source) This happens due to diffraction on the aperture, which has a polygonal ...
user avatar
  • 26.3k
3 votes
1 answer
60 views

Is it possible to take long-distance X-ray images at a high resolution in Earth's atmosphere?

It's my understanding that different wavelengths of EM radiation are affected by scattering and attenuation to varying degrees. Would a camera using only X-rays be able to take a picture of something ...
user avatar
3 votes
1 answer
116 views

Why does shaking our hand result in more copies in dim light than in bright light?

When we wave our hand really fast, we see several facades of it tagging behind. What causes this? I sense this has something to do with the persistence of vision of our eye similar to what happens in ...
user avatar
2 votes
1 answer
65 views

What would a super bright red look like?

I was watching this video which talks about why violet and idigo in the rainbow can be shown on a computer screen even though the computer screen can not produce light with higher wavelength than blue....
user avatar
0 votes
1 answer
150 views

Image reconstruction / generation in the human eye

It is well known how an image is produced in general: You need at least two rays (in geometric optics) to form it, see the image next: But I wonder about these images: As you can see, in the upper ...
user avatar
  • 1,323
2 votes
2 answers
45 views

How things appear to naked eyes at very high frequencies?

We know after a certain frequency our eyes cannot see the changes but how to predict what should be the steady state appearance (of things changing at much higher frequencies )seen by the eyes ? For ...
user avatar
1 vote
3 answers
67 views

How come light in the Violet spectrum looks like a mixture of Red and Blue, even though they are of different wavelength? [duplicate]

How come pure monocromatic light in the violet spectrum is perceived by us as light that is a superposition of 2 other, different wavelength light. is there some scattering process in the eye that ...
user avatar
  • 413
0 votes
0 answers
22 views

Would being nearsighted/astigmatic lead to seeing diffraction patterns from white light?

I am nearsighted with a prescription of greater than -10 diopters and an astigmatism. When I take off my glasses or contacts and look at a source of white light such as a lamp, then I observe white ...
user avatar
  • 1
1 vote
1 answer
89 views

Mathematically rigorous introduction to color theory? (Reference request)

I am looking for an introduction to color theory that presupposes knowledge of considerable mathematics and physics. Such a theory should carefully address how a light spectrum, which can be fully ...
0 votes
1 answer
78 views

Why was RGB chosen as the basis / primary color set for pixels?

Human eyes have retinal cells that are sensitive to red, green, and blue light. Pixels on electronic screens use the same three colors to produce many apparent colors. But a little thought (and ...
user avatar
  • 3,060
0 votes
1 answer
22 views

Can you use something like a polarising material to shift an image horizontally?

A while ago I saw a video that I can’t recall about about some patterns being shifted horizontally with material that causes a polarising effect, I just want to know if that is true? Is it possible to ...
user avatar
  • 1
0 votes
1 answer
35 views

Why do you think people may have different iris but their pupil are black and why when you push your eye at bottom you see two image? [closed]

Why do you think people my have different iris but their pupil are black?
user avatar
0 votes
0 answers
29 views

Stroboscopic effect

Can you explain why exactly when I see the rotating blades of a fan or helicopter, there are dark patches and the patches start rotating slowly and even start moving in the reverse direction when seen ...
user avatar
  • 969
0 votes
3 answers
93 views

If an object emits radiation, is that object visible to us?

I learned that all material objects emit electromagnetic (light) radiation. But, we can only "see" visible light. I'm aware that non-visible light is 'invisible' to us; however, I was ...
user avatar
  • 163
3 votes
0 answers
73 views

Why does the sun not burn your retinas when in peripheral vision?

After going to the ophthalmologist and having bright lights shone in my eyes, I was thinking about how the brightness only hurts when I looked at the light. When it was in my peripheral vision, it ...
user avatar
  • 156
0 votes
1 answer
33 views

Change of position of object with and without glasses/spectacles

If I look at an object with my glasses on and then remove my glasses, the object and everything in my field of vision seem to undergo a displacement. From my judgment, the displacement is greater for ...
user avatar
  • 1,626
0 votes
1 answer
21 views

Does spectacle user able to guess correct distance of object?

It is said in many numericals like a man has near point 100 cm than he need a convex lens that can project a img of obj kept at 25cm at 100cm so that he can watch it clearly! Then my question is, Does ...
user avatar
2 votes
1 answer
220 views

Why I see everything which is red in 3D with my prescription eyeglasses?

I have prescription eyeglasses with -1.5D power (Myopia). I have been wearing eyeglasses for past 5 years and recently changed to blue light filter ones. Now I recognise everything red in colour as a ...
user avatar
1 vote
2 answers
47 views

Why does closing someone's eyes not give them near-sightedness? [closed]

When we close our eyes aren't we technically looking a really close up piece of skin? That is, our eyelids? If it's so close to our eyes why doesn't it give us bad vision? We know if screens or books ...
user avatar

1
2 3 4 5
11