Tagged Questions
2
votes
2answers
51 views
Hyperopia, Far Sightedness
With hyperopia, the focal point is behind the retina, shouldn't this mean that the image is flipped on the retina itself from what is usual?
I must be drawing my ray diagrams wrong.
A little ...
3
votes
4answers
235 views
Eye sensitivity & Danger signal
Why are danger signal in red, when the eye is most sensitive to yellow-green?
You can check luminosity function for more details...
5
votes
2answers
137 views
What is the minimum optical power detectable by human eye?
If one is in complete darkness, what is the minimum optical power that the eye can "see" (let's say in 500-600 nm range).
I found that for 510 nm, 90 photons can be detected ...
4
votes
1answer
72 views
Human eyes vs aberrations
There are no perfect lenses in nature. Aberrations of some kind will always be there. But why healthy human eyes circumvent this issue? Or, are there any aberrations we don't "see?"
6
votes
2answers
478 views
Why do green lasers appear brighter and stronger than red and blue lasers?
This is mostly for my own personal illumination, and isn't directly related to any school or work projects. I just picked up a trio of laser pointers (red, green, and blue), and I notice that when I ...
-1
votes
1answer
127 views
How do photo mosaic work from eye and image processing perspective? [closed]
Hello fellow investigators
I have two question about optical illusions
1) A photo mosaic is something like this http://i.stack.imgur.com/Pzplp.png
What are the optical principles behind our eye ...
0
votes
1answer
69 views
What is the new distance for resolution of the images? [closed]
The taillights of an automobile are $1.25\:\rm{m}$ apart. Assume the pupil of a person's eye has a diameter of $5\:\rm{mm}$ and the light has an average wavelength of $604\:\rm{mm}$. At night, on a ...
0
votes
1answer
68 views
How to determine the angle a camera has to be at to image a desired scene, given the camera parameters?
Reviewing old material I learned years ago, having a hard time rewrapping my head around the relationships in capturing images from a camera.
Imagine a scenario with the camera placed on the ground ...
1
vote
1answer
116 views
How does the focal length of the lens change the distance from the camera to an object?
I am reviewing some old image processing notes and have the following problem:
I have a camera with a projection plane of $2cm\ by\ 2cm$ and a $15mm$
lens. If you want an $1.5m$ object to take ...
2
votes
1answer
559 views
How to determine the field of view for a pinhole camera with given parameters?
I am reviewing some old material I learned years ago and am having trouble figuring this one out. Can somebody confirm that I have done my math correctly, and tell me how I can recover the field of ...
5
votes
2answers
571 views
Infrared remote flashes blue light in camera
I know that if you held an infrared remote in front of a digital camera, it'll flash a blue/purplish light when you press the buttons. Why?
2
votes
1answer
506 views
Effects of high frequency lighting on human vision?
I have a couple of different LED flashlights. One of them has three different "modes" of brightness, and the way it controls it is via pulse width modulation (PWM). Here is a picture that illustrates ...
2
votes
1answer
219 views
How to determine the required resolution to view an image at a certain size?
If I have several camera specifics, can I determine the required resolution to view an image at the size I want?
For example, let's say I want a picture of a square painting to be at least ...
2
votes
4answers
469 views
Why are color values stored as Red, Green, Blue?
I learned in elementary school that you could get green by mixing blue with yellow.
...
13
votes
1answer
2k views
Why can you see virtual images?
In optics it is widely mentioned real images are projectable onto screens whereas virtual ones can only be seen by a person. Isn't that contradictory? I mean in order to see the virtual image it has ...
5
votes
5answers
3k views
Eyes open under water
Yesterday I looked underwater with my eyes open (and no goggles) and I realized I can't see anything clearly. Everything looks very, very blurry. My guess is that the eye needs direct contact with air ...
