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Published byKenneth Harvey Modified over 9 years ago
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From the spectrum lab: Light waves with different wavelengths appear as different colors. Short waves are blue/purple. Long waves are red.
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Missing colors? Can you find these colors in the spectrum?
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More than just wavelength... There is no “brown” or “pink” wavelength of light. Color is a PERCEPTION, not a reality. That is: – Color only exists in your mind.
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False motion
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Scintillating Blocks
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Shadow and Color
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White’s Illusion
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Opponent Afterimage
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McCollough Effect
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Color opponency
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What is going on? You cannot trust your brain. Your perception of the world is different than the actual world.
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Other color craziness [Greenpro2009 videos: chameleon, color constancy] [Himba Tribe study]
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Real spectra... Objects emit/reflect light with different sets of wavelengths. – Bright in areas, dark in others:
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Perfect emitter at 4000 K:
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The Sun:
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Electrified neon gas
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Spectra and the eye Eyes can’t see all that detail. Can’t measure the amount of light of every wavelength. They check THREE PARTS of the spectrum... – red, green, and blue parts
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Rods and Cones Four types of light-detecting cell in your eye: – Rods: very sensitive to all light – Cones: less sensitive, tuned to certain colors (Red, Green, Blue)
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Rods and Cones Sensitivity of the 3 cone cells:
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Primary colors 3 cones → 3 primary colors Computers and TVs display colors with an “RGB” system for Red, Green, and Blue.
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RGB Pixels
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Color Addition
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Primary colors “Red, yellow, blue” are a BAD CHOICE for primary colors. Even in pigments! They can’t make a full color gamut (range). Cyan, Magenta, and Yellow form the CMYK system for pigment/ink.
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Color Subtraction
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Different numbers of cones Some humans only have 2 types of cone! They are color deficient or color blind. (About 1% of men.) Some women may have 4 cones!! They’d see differences in color that nobody else does! Tetrachromacy in humans is a new, uncertain discovery.
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Colorblindness test
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Colorblind simulation: red-green def. blue-yellow def.
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Cones in other animals Most mammals have 2 types. – Dogs don’t see in black & white! – It’s just a limited set of colors. Higher primates have 3 types. Some birds, reptiles, and insects have 4 or even 5!
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Different cone sensitivity The cone cells in most birds and insects can detect ultraviolet! Many things have “hidden” features that they can see!
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