I always learned “ROYGBIV” as the colors of the rainbow. Red, orange, yellow, blue, indigo, violet.

What’s up with the last two? Isn’t indigo basically just dark blue? Why is it violet and not purple? Can’t it just be “ROYGBP”?

  • floofloof@lemmy.ca
    303·
    1 year ago

    It doesn’t contain pink or brown. Some of the colours we see are how we register a mixture of light frequencies, whereas each point in the rainbow is just a single frequency.

    • Dr Cog@mander.xyz
      94·
      1 year ago

      This is incredibly incorrect. While many colors that are additive are combinations, those combinations are simply approximations of the single wavelength true color. All colors are on a spectrum of hue, luminance (brightness) and intensity (saturation).

      Pink is red with high luminance and high intensity, and brown is orange with low luminance and mid-high intensity

      • TonyTonyChopper@mander.xyz
        5·
        1 year ago

        Nope. A whole bunch of colors do not correspond to any wavelength of light. This includes purple.

        Among some of the colors that are not spectral colors are:

        Grayscale (achromatic) colors, such as white, gray, and black. Any color obtained by mixing a gray-scale color and another color (either spectral or not), such as pink (a mixture of a reddish color and white), or brown (a mixture of orange and black or gray). Violet-red colors, which in color theory include line of purples colors (such as, approximately, magenta and rose), and other variations of purple and red. Impossible colors, which cannot be seen under normal viewing of light, such as over-saturated colors or colors that are seemingly brighter than white. Metallic colors which reflect light by effect.

        https://en.wikipedia.org/wiki/Spectral_color#Extra-spectral_colors

      • floofloof@lemmy.ca
        2·
        1 year ago

        Pink can also be described as a reddish hue with high brightness and low saturation. But saturation is a matter of how strongly one frequency is emphasized compared to other frequencies. So colors with low saturation contain mixtures of frequencies, but each point in the rainbow, when there’s no other source of light present, is only a single frequency. This is why the rainbow doesn’t contain any desaturated colors like pink. Brown, I admit, can be just dark orange.