> extremely frustrating when someone uses "violet" to mean "purple" (or vice-versa) in a technical context. E.g. if I buy a "violet" photo filter, I will be extremely disappointed if it turns out to be dark magenta/purple.
If you are buying a photo filter you should look for a chart showing what specific wavelengths of light it absorbs.
Neither “purple” nor “violet” is a technical term.
> hundreds of years ago, "blue" was used to refer to what we would now think of as "cyan", and "indigo" was used to refer to what we would now think of as "blue" (0x0000FF on a computer monitor).
0x0000FF on your computer display is not anything like “unique blue” (some blue color a typical observer would say is neutral between green and red). Arguably calling computer-display primaries “blue” is a huge mistake.
Reasonable unambiguous human-comprehensible names for the RGB primaries would be something like “orangish red” (or even “reddish orange” if you take the ISCC–NBS color category name), “yellowish green”, and “purplish blue”.
> The colour people typically refer to as "cyan" in RGB colourspace (0x00FFFF) is the same colour referred to as "cyan" in the CMYK colourspace used for printing.
The +, ◻, and × are printer’s “cyan”, (the ISCC–NBS named category for this is “greenish blue”) and the triangle shows the mixture of sRGB B and G (right at the edge of the ISCC–NBS category “bluish green”).
In a similar way, printer’s magenta is a purplish red color, whereas the 0xFF00FF on a computer display is very slightly reddish purple. The two are not remotely similar.
Notice that diagram also shows dotted lines for the NCS “unique hues” of red, yellow, green, blue, and also shows round dots for the world color survey’s color category foci.
> have you considered having the spectral sensitivity of your eyes tested?
Yes, I have normal color vision, can perfectly pass a Farnsworth-Munsell 100 hue test, etc.
OK, I acknowledge that I was in error here about RGB full-saturation green + blue being equivalent to printer's cyan, and apologize for the error. However, they are still both (in my mind) firmly in the category of "colours in the sky on a cloudless day".
I think we're going to have to agree to disagree on the rest, but thank you for teaching me some new things today.
If you are buying a photo filter you should look for a chart showing what specific wavelengths of light it absorbs.
Neither “purple” nor “violet” is a technical term.
> hundreds of years ago, "blue" was used to refer to what we would now think of as "cyan", and "indigo" was used to refer to what we would now think of as "blue" (0x0000FF on a computer monitor).
0x0000FF on your computer display is not anything like “unique blue” (some blue color a typical observer would say is neutral between green and red). Arguably calling computer-display primaries “blue” is a huge mistake.
Reasonable unambiguous human-comprehensible names for the RGB primaries would be something like “orangish red” (or even “reddish orange” if you take the ISCC–NBS color category name), “yellowish green”, and “purplish blue”.
> The colour people typically refer to as "cyan" in RGB colourspace (0x00FFFF) is the same colour referred to as "cyan" in the CMYK colourspace used for printing.
These are not close at all. Look at the chart I made in 2010, https://upload.wikimedia.org/wikipedia/en/e/ed/Color-map-2.p...
The +, ◻, and × are printer’s “cyan”, (the ISCC–NBS named category for this is “greenish blue”) and the triangle shows the mixture of sRGB B and G (right at the edge of the ISCC–NBS category “bluish green”).
In a similar way, printer’s magenta is a purplish red color, whereas the 0xFF00FF on a computer display is very slightly reddish purple. The two are not remotely similar.
Notice that diagram also shows dotted lines for the NCS “unique hues” of red, yellow, green, blue, and also shows round dots for the world color survey’s color category foci.
> have you considered having the spectral sensitivity of your eyes tested?
Yes, I have normal color vision, can perfectly pass a Farnsworth-Munsell 100 hue test, etc.