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Blue TV Screen Illusion

  1. Sep 5, 2011 #1
    If the blue screen on your TV is only 1/3 blue, 2/3 black, why do we see it as blue?

    (Each pixel on a Cathode Ray Tube TV is made up of 3 phosphor dots, red green and blue, so when you have a blue screen, only the blue dot is lit up).
  2. jcsd
  3. Sep 7, 2011 #2


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    The blue pixels are the only ones that are giving off any light, so they are the only ones you can see. Black is merely the absence of light or color.
  4. Oct 12, 2011 #3
    True, but when the TV is turned off I can still see the dark screen just as much as I can see the blue screen when it's turned on.
    So why if 2/3 of the screen is black, the screen still looks blue?
  5. Oct 12, 2011 #4


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    Get real close with a magnifying glass and you should see little blue dots. Since they are the only thing radiating (black is the ABSENCE of radiation) they are the only thing you see.
  6. Oct 12, 2011 #5


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    It has to do with resolution, if you get close enough you can see the individual pixels. When you are too far away the blue and black pixels were merge and only the emitted light from the blue pixels will be seen. The black pixels still have an influence, since obviously the intensity of the light will be less than when all the pixels would have been blue.
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