Cone outputs can subtract and add {opponency} {color opponent process} {opponent color theory} {tetrachromatic theory}.
red-green opponency
Middle-wavelength cone output subtracts from long-wavelength cone output, L - M, to detect blue, green, yellow, orange, pink, and red. Maximum is at red, and minimum is at blue. See Figure 1. Hue calculation is in lateral geniculate nucleus, using neurons with center and surround. Center detects long-wavelengths, and surround detects medium-wavelengths.
blue-yellow opponency
Short-wavelength cone output subtracts from long-wavelength plus middle-wavelength cone output, (L + M) - S, to detect violet, indigo or ultramarine, blue, cyan, green, yellow, and red. Maximum is at chartreuse, minimum is at violet, and red is another minimu is at red. See Figure 1. Saturation calculation is in lateral geniculate nucleus, using neurons with center and surround. Luminance output goes to center, and surround detects short-wavelengths [Hardin, 1988] [Hurvich, 1981] [Katz, 1911] [Lee and Valberg, 1991].
brightness
Long-wavelength and middle-wavelength cones add to detect luminance brightness: L + M. See Figure 1. Short-wavelength cones are few. Luminance calculation is in lateral geniculate nucleus, using neurons with center and surround. Center detects long-wavelengths, and surround detects negative of medium-wavelengths. Brain uses luminance to find edges and motions.
neutral point
When positive and negative contributions are equal, opponent-color processes can give no signal {neutral point}. For the L - M opponent process, red and cyan are complementary colors and mix to make white. For the L + M - S opponent process, blue and yellow are complementary colors and mix to make white. The L + M sense process has no neutral point.
color and cones
Red affects long-wavelength some. Orange affects long-wavelength well. Yellow affects long-wavelength most. Green affects middle-wavelength most. Blue affects short-wavelength most.
Indigo or ultramarine, because it has blue and some red, affects long-wavelength and short-wavelength. Violet, because it has blue and more red, affects long-wavelength more and short-wavelength less. Magenta, because it has half red and half blue, affects long-wavelength and short-wavelength equally. See Figure 1.
White, gray, and black affect long-wavelength receptor and middle-wavelength receptor equally, and long-wavelength receptor plus middle-wavelength receptor and short-wavelength receptor equally. See Figure 1. Complementary colors add to make white, gray, or black.
color and opponencies
For red, L - M is maximum, and L + M - S is maximum. For orange, L - M is positive, and L + M - S is maximum. For yellow, L - M is half, and L + M - S is maximum. For green, L - M is zero, and L + M - S is zero. For blue, L - M is minimum, and L + M - S is minimum. For magenta, L - M is half, and L + M - S is half.
saturation
Adding white, to make more unsaturation, decreases L - M values and increases L + M - S values. See Figure 1.
evolution
For people to see color, the three primate cone receptors must be maximally sensitive at blue, green, and yellow-green, which requires opponency to determine colors and has color complementarity. The three cones do not have maximum sensitivity at red, green, and blue, because each sensor is then for one main color, and system has no complementary colors. Such a system has no opponency, because those opponencies have ambiguous ratios and ambiguous colors.
Consciousness>Consciousness>Sense>Vision>Color Vision
1-Consciousness-Sense-Vision-Color Vision
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Date Modified: 2022.0224