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Objects' color to our vision

  1. Aug 13, 2015 #1
    hi guys, i just read a passage about colors to our vision
    it is a fact that we see an apple being red because it reflects red and absorbs the rest of the colors
    so my question is, is it possible to change the amount of reflection and absorption of an object and hence we see it with a different color?
    for instance, by changing some conditions, the apple no longer reflects the red color but absorb it while reflecting the yellow color so we see that apple being yellow

    gracias:smile:
     
  2. jcsd
  3. Aug 13, 2015 #2

    A.T.

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    Yes, by painting it for example.
     
  4. Aug 13, 2015 #3
    haha absolutely i know:wink:
    but if there are any physical ways to change the absorption of colors of objects?
     
  5. Aug 13, 2015 #4

    A.T.

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    If you don't want to coat it with a different material, then you have to change the surface material of the object itself, with chemicals, radiation etc.
     
  6. Aug 13, 2015 #5
    okay thanks:)
     
  7. Aug 13, 2015 #6

    A.T.

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  8. Aug 13, 2015 #7

    sophiecentaur

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    There are photochromic dyes, which change colour as you heat them up. (Remember the T shirts and kids' pyjamas?) They absorb different wavelengths at different temperatures. Also, some Liquid Crystals will reflect and transmit different wavelengths at different tem[peratures (remember the Feverscan LC thermometers that we put on kids' heads instead of sticking a normal thermometer in their mouths (or elsewhere`~!!!)
    Here is a terminology problem. The object will reflect and absorb different Wavelengths and, thus alter the colour that we observe. Colour is totally in our head. People happen to agree on what, broadly, to call the various colours and will, again broadly, agree when colours 'match' for two different objects. But all that is subjective and very much a shorthand that our brain uses to assess the spectral content of what the eyes receive.
     
  9. Aug 13, 2015 #8

    CWatters

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    Peel it :-)
     
  10. Aug 13, 2015 #9

    CWatters

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    +1. It might be possible to make an apple look any colour you want using Hypnosis.

    http://www.livescience.com/21275-color-red-blue-scientists.html

     
  11. Aug 13, 2015 #10

    sophiecentaur

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    "One person's red might be another person's blue and vice versa, the scientists said. You might really see blood as the color someone else calls blue, and the sky as someone else's red."

    It is true that context and culture can cause different people to 'see' things as different colours. If you get people to paint a picture of the Sea from memory, then you can expect a huge range of outcomes, from brown thru green to blue, via grey. Even when given the same scene, you could expect different versions. The same could apply to blood - which actually takes on a fairly wide range of hues.
    However, I really doubt that someone with 'normal' colour vision who has been exposed to a normal range of colours in life would not perform pretty much the same way as anyone else in a lab test, using sample swatches of colours, when asked to match them together. Of course, the Names they use for the colours could be very different but that's a different matter.
    The tristimulus theory of colour vision is pretty well tested and seems to show that most people see and group the colours they 'appreciate' in pretty much the same way. Colour TV and Photography work pretty successfully using that basic method of analysis and synthesis..
     
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