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How Does Light Help Us See?

  1. Jan 27, 2014 #1
    If light is electromagnetic radiation, when it reflects off objects and travels to our eyes, how is the information of the object carried?

    Is it because of dispersion? Does light travel at different speeds depending on what part of the object it reflects off to help our brain form colours and distinct features of the object?
  2. jcsd
  3. Jan 27, 2014 #2


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    Light always travels at the speed of light.

    It is primarily direction and intensity that carries the information. If the light hits a particular place on your retina, it must have come from a particular direction. The lens in your eye assists in this process by focusing so that the light that comes from a particular point on the object lands on a particular place on your retina. This part of the process is well understood. It is the science of optics. It is the same way that a camera works.

    The light and dark patches on the retina, in effect form a two-dimensional map -- an image -- of what we can see with our eyes. Processing in the optical cortex does things like edge detection to recognize the outlines of shapes. Various cues are used to infer distance and direction and thereby recognize a three dimensional shape based on the two two-dimensional images (one from each eye).

    Color also carries information, but edge detection keys primarily on black and white contrast.
  4. Jan 27, 2014 #3


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    No it doesn't. Our brain have learnt receiving information from outside and "creating" the world that we see.
    That's why it is also subject to illusions for example.
  5. Jan 31, 2014 #4

    Claude Bile

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    The plane-wave (direction) spectrum gives spatial information, while the temporal (frequency) spectrum yields colour information.

  6. Jan 31, 2014 #5


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    The intensity / direction distribution is the prime factor. BTW, nearby objects are not producing plane waves at the entrance to our pupils
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