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Nothing can currently, without a display that was fully spectral, and that doesn’t exist. Seems a little lean on the color science front. colour-science.org co

Nothing can currently, without a display that was fully spectral, and that doesn’t exist. Seems a little lean on the color science front. colour-science.org could have done all of this, with much greater focus on the science.

kelsolaar 7y ago
I would like to add that the problem with the codedrome.com implementation is that it is relying on an approximation to convert wavelengths to RGB, it is a shame because you really just need the Colour Matching Functions (CMFs) data for the Standard Observer of interest, i.e. 2deg or 10deg (https://github.com/colour-science/colour/blob/develop/colour/colorimetry/datasets/cmfs.py#L1372 https://github.com/colour-science/colour/blob/develop/colour...) and a 3x3 matrix to convert from CIE XYZ to the RGB colourspace of interest, e.g. sRGB (https://github.com/colour-science/colour/blob/develop/colour/models/rgb/datasets/srgb.py#L87 https://github.com/colour-science/colour/blob/develop/colour...).
aj7 7y ago
No. We are not display-bound. There are tunable lasers and optical parametric oscillators commercially available that will output a specific frequency under computer control, throughout the visible spectrum. There are also frequency comb laser devices that emit a picket fence of frequencies, spanning the visible spectrum, each with a precisely known frequency. Tunable laser sources exist from the far infrared to the vacuum ultraviolet.
- colanderman 7y ago
  I think it's fair to say that, as far as commercially available consumer computer displays are concerned (and thus anything relevant to anyone viewing the OP website), we are indeed display-bound.
  - kelsolaar 7y ago
    And given consumer media are RGB encoded (or any triplet of colour flavour), it will be long before having consumer displays with more than 3 usable bands. Sharp Electronics had a display with RGBY(ellow) filters, i.e. Quattron (https://en.wikipedia.org/wiki/Quattron https://en.wikipedia.org/wiki/Quattron), but no media existed with the 4 required channels, not only that but there was no Yellow primary thus it was "useless".
    - zamadatix 7y ago
      Given we are trichromats I don't get why we would need a 4th band to cover more colors instead of continuing to expand the current 3 bands until the resulting color space encompasses our own.
      - colanderman 7y ago
        Short answer: because the space of real colors is convex. It cannot be fully encompassed by any linear combination of three (or in fact, any finite number of) real primaries. You can entirely encompass it using imaginary primaries, which is what some color spaces do (e.g. ProPhoto RGB), but it is physically impossible to manufacture a linear primary-based display which does. Adding extra primaries however does greatly help. DLP did this by having 6 (I think) primaries, but I don't think it was widely taken advantage of. For a visual representation of the problem, look at the first diagram on https://en.wikipedia.org/wiki/Color_space https://en.wikipedia.org/wiki/Color_space and imagine how to encompass the colored region using a linear combination of three (or more) points within said region. (You can't.) For the long answer, study up on human tristimulus response curves and how those interact to create the Planckian locus on CIE xy colorimetry diagrams.
    - colanderman 7y ago
      You don't need a 4th primary to represent all visible colors. You just need imaginary primaries. Heck, even something with real primaries like Rec. 2020 [1] can represent information outside the standard sRGB primaries that a 4th primary would be useful to display. (Granted, a better choice of green primary would work better in that specific case, but such choices aren't always physically realizable.) Another use is enhancing saturation of an image. My DLP projector has a mode like this to take advantage of its 6 primaries. Enhancing saturation can produce a convex gamut even from a non-convex one (e.g. sRGB), the only means of reproducing of which may be with additional primaries. By my estimation, the main problem with Quattron wasn't that it had a 4th primary, which is legitimately useful. It's that - as you point out - it didn't. It literally did not have a yellow primary; just a yellow filter illuminated by the red and green primaries. Thats, like, total hokum.

kelsolaar 7y ago

I would like to add that the problem with the codedrome.com implementation is that it is relying on an approximation to convert wavelengths to RGB, it is a shame because you really just need the Colour Matching Functions (CMFs) data for the Standard Observer of interest, i.e. 2deg or 10deg (https://github.com/colour-science/colour/blob/develop/colour/colorimetry/datasets/cmfs.py#L1372 https://github.com/colour-science/colour/blob/develop/colour...) and a 3x3 matrix to convert from CIE XYZ to the RGB colourspace of interest, e.g. sRGB (https://github.com/colour-science/colour/blob/develop/colour/models/rgb/datasets/srgb.py#L87 https://github.com/colour-science/colour/blob/develop/colour...).

aj7 7y ago

No. We are not display-bound. There are tunable lasers and optical parametric oscillators commercially available that will output a specific frequency under computer control, throughout the visible spectrum. There are also frequency comb laser devices that emit a picket fence of frequencies, spanning the visible spectrum, each with a precisely known frequency. Tunable laser sources exist from the far infrared to the vacuum ultraviolet.

colanderman 7y ago
I think it's fair to say that, as far as commercially available consumer computer displays are concerned (and thus anything relevant to anyone viewing the OP website), we are indeed display-bound.
- kelsolaar 7y ago
  And given consumer media are RGB encoded (or any triplet of colour flavour), it will be long before having consumer displays with more than 3 usable bands. Sharp Electronics had a display with RGBY(ellow) filters, i.e. Quattron (https://en.wikipedia.org/wiki/Quattron https://en.wikipedia.org/wiki/Quattron), but no media existed with the 4 required channels, not only that but there was no Yellow primary thus it was "useless".
  - zamadatix 7y ago
    Given we are trichromats I don't get why we would need a 4th band to cover more colors instead of continuing to expand the current 3 bands until the resulting color space encompasses our own.
    - colanderman 7y ago
      Short answer: because the space of real colors is convex. It cannot be fully encompassed by any linear combination of three (or in fact, any finite number of) real primaries. You can entirely encompass it using imaginary primaries, which is what some color spaces do (e.g. ProPhoto RGB), but it is physically impossible to manufacture a linear primary-based display which does. Adding extra primaries however does greatly help. DLP did this by having 6 (I think) primaries, but I don't think it was widely taken advantage of. For a visual representation of the problem, look at the first diagram on https://en.wikipedia.org/wiki/Color_space https://en.wikipedia.org/wiki/Color_space and imagine how to encompass the colored region using a linear combination of three (or more) points within said region. (You can't.) For the long answer, study up on human tristimulus response curves and how those interact to create the Planckian locus on CIE xy colorimetry diagrams.
  - colanderman 7y ago
    You don't need a 4th primary to represent all visible colors. You just need imaginary primaries. Heck, even something with real primaries like Rec. 2020 [1] can represent information outside the standard sRGB primaries that a 4th primary would be useful to display. (Granted, a better choice of green primary would work better in that specific case, but such choices aren't always physically realizable.) Another use is enhancing saturation of an image. My DLP projector has a mode like this to take advantage of its 6 primaries. Enhancing saturation can produce a convex gamut even from a non-convex one (e.g. sRGB), the only means of reproducing of which may be with additional primaries. By my estimation, the main problem with Quattron wasn't that it had a 4th primary, which is legitimately useful. It's that - as you point out - it didn't. It literally did not have a yellow primary; just a yellow filter illuminated by the red and green primaries. Thats, like, total hokum.