The Color of White Light

(ludens.cl)

24 points | by xk3 3 days ago

3 comments

  • somat 58 minutes ago
    I sort of wonder is there a "true" way to represent color? Would a intensity over frequency curve do it?

    I probably lack the terminology to express myself properly, but color ends up being a very human thing, with a huge focus on primary colors(the colors that match the frequency response of the human eye) This is fine, we are human after all, but then I always feel color theory dives off the deep end, with color wheels and complimentary colors and triplets, etc. why? there is nothing physically cyclic going on. It never makes any sense to me that patterns based on it being cyclic would be any better than just picking colors. Any way, silly rant aside, if we wanted to define an objective physical color format, how would it be done?

    • lefra 3 minutes ago
      The term you're looking for is "color space".

      Depending on what you want to do there's CIE XYZ (maps spectrum of color to a 3 component vector by integrating the spectrum multiplied by three functions), CIE Lab* (describes the color of objects under a specified illuminant), CIE Luv* (to characterize emissive source, nonlinear so the the distance between colors corresponds to perceived differences).

      These color spaces are built to objectively describe colors, as seen by a human with typical color vision.

    • praash 6 minutes ago
      > Would a intensity over frequency curve do it?

      That should work as a brute-force method. You could simulate lighting conditions by measuring the reflected spectrum of different materials and multiplying with the spectrum of a light source.

      Check out the CIE XYZ color space and its color matching functions. It's the standard for defining/converting color spaces and calibrating displays for accurate color matching.

      https://en.wikipedia.org/wiki/CIE_1931_color_space

    • RedNifre 44 minutes ago
      You could go a long way by specifying the reflectiveness over the visible light spectrum and then do the same for light sources. That way, you could do GDR style truly monochrome sodium vapor lamps, which makes telling colors apart impossible.

      To do neon colors, you would need some sort of frequency redirect in your texture data as in "this pixel absorbs 80% infrared, but reemits it as visible red". Then you could have black light light sources and cool poster textures as well.

      I think doing textures in this format would take too much space, but doing a 256 color palette that way might be fine.

    • andsoitis 35 minutes ago
      > I sort of wonder is there a "true" way to represent color? Would an intensity over frequency curve do it?

      There’s no single “true” way because color isn’t a fixed property of light itself, it’s the result of how a visual system interprets wavelengths.

      Having said that, if you’re looking for an objective way that doesn’t depend on observer, you could use spectral power distribution.

      That would be the mix of wavelengths present, plotted as intensity vs. wavelength.

      That’s because a single wavelength (say 580nm) produces one specific color sensation, but many different combinations of wavelengths can produce that identical sensation (called metamers), so representing color by wavelength alone isn’t even uniquely “true” perceptually.

    • phito 49 minutes ago
      Colors only exist in the human brain, they're qualia, interpreted from the mixture of wavelengths our eyes detect.
    • dmd 49 minutes ago
      “I’ve thought about this for five minutes, and it seems so simple. It must be the tens of thousands of vision scientists and psychophysicists who have worked on this for the last century who have all missed how simple it is.”
  • miladyincontrol 3 days ago
    CRI of lights is definitely a large factor in my purchasing these days. The muting, compressive response of some lights almost pains me at this point.

    As this post's author noted white LEDs can be pretty solid. Bulbs that have a mix of white LEDs at various temperatures to be "bi-color" tend to be pretty solid as well. Its once you go towards RGB light bulbs that you tend to get a fairly iffy CRI.

    I've referenced https://optimizeyourbiology.com/light-bulb-database and https://optimizeyourbiology.com/smart-light-database before when looking at bulbs but if anyone has a better resource, absolutely please drop a reply.

    • StilesCrisis 51 minutes ago
      I'd be curious to understand exactly how CRI equates to the charts in this post!
  • deadlast2 46 minutes ago
    Sun is white light. Wonder what that means. Brightest object in out awareness is modeled as clean white. Or is this the actual basic color.
    • Sharlin 35 minutes ago
      There are no objective "basic colors". What "white" means is "excites our different types of photoreceptors roughly equally". And the photoreceptors have the sensitivity curves that they do because of our sun’s surface temperature and a convenient "window" in the opacity of our atmosphere. Organisms evolved under a different star, within a different atmosphere would have a different idea of what a "neutral" color is.

      (Because of additional processing done by our visual system, what looks "white" to us is very dependent on the color of the ambient light. But the ~5800 K blackbody spectrum could be called the "most neutral" white to our eyes because that’s what evolution has optimized them for.)

    • andsoitis 41 minutes ago
      [dead]