why is yellow brighter than other colors?

Discussion in 'Free Thoughts' started by allisone417, Nov 30, 2005.

  1. allisone417 i'll be in my room Registered Senior Member

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    why is pure yellow brighter/more intense than other pure colors, such as blue and violet?
     
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  3. glaucon tending tangentially Registered Senior Member

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    It's not.
    What makes you think it is??
     
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  5. allisone417 i'll be in my room Registered Senior Member

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    i dont know!
     
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  7. glaucon tending tangentially Registered Senior Member

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    There you go then.
     
  8. pilpaX amateur-science.com Registered Senior Member

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    red green and blue are "pure" colors,
    yellow is not

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  9. allisone417 i'll be in my room Registered Senior Member

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    thank you
     
  10. glaucon tending tangentially Registered Senior Member

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    Actually, that answer is wrong. That scenario only applies to Additive colour theory, whereas real life observes Subtractive colour theory rules.
     
  11. Mmmmm, think you'll find Red, Blue and Yellow are the three primary colours - Green is produced by mixing Blue and Yellow, making it a Secondary.
     
  12. glaucon tending tangentially Registered Senior Member

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    This is correct.
     
  13. Professor Marvel Registered Member

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    I wasn't so sure about real life observing subtractively so I Googled it and came up with this from the Franklin Institute :

    **********************
    Additive Color
    As stated previously, the primary colors of light are red, blue, and green. These occur in the Additive Color (RGB) Model, so named because black is the base and light is "added" to eventually get to white, which is all of the colors together. Additive colors are seen in televisions, nature, and the computer screen you are looking at right now. Amazingly enough, colors are perceived in our eyes and brains by a three-color code; three different particles in the retina are sensitive to—you guessed it—red, blue, and green. Just as any color of the spectrum can be made by mixing the three primary colors, so do our own eyes discern the various colors by sensing different wavelengths with these three receptors.
    ***********************

    ___________________________________________
    “I had a rational idea this morning but I didn’t like it.”
     
  14. teguy Registered Senior Member

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    http://www.luminous-landscape.com/tutorials/colour_theory.shtml

    Yes, it is.

    See the link above.

    It is generally assumed that white is the brightest colour but in fact yellow is: To demonstrate, you can take a black and white foto and compare white coloured object to yellow coloured one, the latter appears to be brighter.
    best,
     
  15. glaucon tending tangentially Registered Senior Member

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    Correct, as far as the models go, but you didn't read far enough. Colour, in nature, is 'created (sic)' via the additive model, but what we perceive transpires via the subtractive model process. The colour of a perceived object is that colour wavelength which is reflected (not absorbed) by the object. This is why black objects will be hotter to the touch than white objects; verry little light is reflected off. When you have a white-light source (say, a powerful lamp) and superimpose coloured gels, that colour will be seen. If you layer red, blue and green gels, you'll get white again (as additive theory predicts). This is the exact opposite of what happens if say, you mix together colour sources of a natural origin (pigments, dyes, etc.). Try mixing up red, green and blue paints and you'll end up with brown (it would be black if you had sufficient chroma depth in the paints). This is subtractive theory.
     
  16. valich Registered Senior Member

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    Pilpax's diagram above shows you that white is brighter than yellow. It all depends on how the retina cone in your eyes perceive the light but white is brighter than any other color because it is not absorbed by any medium: it still remains pure white. Other colors are refraction colors of white: they are split up from it. When white passes through a colored medium, a certain amount of it is absorbed.

    Visible wavelengths cover a range from approximately 400 to 800 nm. The longest visible wavelength is red and the shortest is violet. Ultraviolet radiation have wavelengths less than 200 nm and causes sunburn and in some cases cancer (melanoma). White consists of all the visible ranges of the colors that we can see. Brigthness of ANY light color is measured does not depend on the color, it depends on the "luminance" of that color: the luminous intensity. This intensity depends on "the amount of light that passes through or is emitted from a particular area," or the "density of luminous intensity in a given direction." Wikipedia
     
  17. Roman Banned Banned

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    Define bright.
    Is it subjectively measured by an individual on a 1 to 10 scale by comparing all colors to other colors? Or would you measure the number of photons bouncing back, or the frequency of waves, or the energy in retained in the waves being reflected?

    White would be brightest if brightness was the amount of energy being bounced back, as white absorbs the fewest (~0) wavelengths.
     
  18. Hapsburg Hellenistic polytheist Valued Senior Member

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    Because it's yellow.
    Yellow is bright because yellow is bright, and yellow is yellow because it's yellow.
     
  19. Communist Hamster Cricetulus griseus leninus Valued Senior Member

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    Only in paints. In light, it is Red, Green and Blue. Hence RGB
     
  20. valich Registered Senior Member

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    I said, white would be the brightest - luminosity factors being the same - because none of its wavelengths are absorbed by other colors: it is pure light. All other colors are a refraction of white light through a medium, like splitting them up in a prism does. The perception of light is biologically influenced by the three different color photoreceptors in the retina cones in our eyes.

    The range of the visible spectrum that we can see is between about 400-800 nm (nanometer) wavelengths. This visible range can also be measured in terms of frequency Hz (Hertz). But what determines brightness is luminance, measured in candelas (radiation of frequency) per square meter (cd/m2).

    With equal luminisity, the human eye is most sensitive to the color green. "At other frequencies, more radiant intensity [brilliance] is required to achieve the same luminous intensity."

    Colors in nm:
    Infrared >1000
    Red 700
    Orange 620
    Yellow 580
    Green 530
    Blue 470
    Violet 420
    Near ultraviolet 300
    Far ultraviolet <200

    Source: Wikipedia:colors http://en.wikipedia.org/wiki/Colors
     

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