pink in xcolor is different from pink in Groff, X11, Wikipedia, HTML, and CSS

[ghost]

Continuing https://tex.stackexchange.com/questions/656526 (thanks to Ulrike and wipet for an answer and comments there!) , the RGB value for pink from xcolor.dtx is % \Color{pink} = \Color{red}|!|25 in comments and 1,.75,.75 in code, which translates to 255 191.25 191.25 (decimal) ≈ FF BF BF (hexadecimal), whereas the RGB value for pink in Groff, X11, Wikipedia, HTML, and CSS is 255 192 203 (decimal) = FF C0 CB (hexadecimal). Upon a quick Web search, we found no support for pink being exactly FF BF BF (though some sites approximate it as “Your Pink”) and an overwhelming support for pink being exactly FF C0 CB.

(Off-topic: Purely subjectively, if I were asked, which of the two colors is more pink, https://www.colorhexa.com/ffc0cb.png or https://www.colorhexa.com/ffbfbf.png , I'd probably go with ffc0cb and say that ffbfbf is nearer to a light red. When we think of it, this feeling corresponds to the aforementioned \Color{red}|!|25.)

Any good intention (or a good reason which may or may not be valid today) for why xcolor.sty assigned 1,.75,.75 to pink? Or was that a typo, perhaps, or a (rounding) error when translating from some non-RGB color-naming scheme, or a translation from an old low-bit color-naming scheme? Or, perhaps, some other reason for reducing the green and blue parts simultaneously by 25%? Or the color pink according to the ANSI/ISO/DIN/ГОСТ/RAL/NCS standard №… ?

Taking a look at the website of the maintainer from 2003-2021, we also learn that the maintainer is probably German, and Engl. pink can be translated to German both by Ger. Rosa traditionally (with a difference in color!) and Ger. Pink in a more modern way. The flowers giving the two German names differ. So, the difference in the RGB value might have hypothetically emerged due to a vagueness in translation. We don't know as of now.

Having the same name for two different colors in an undocumented way is clearly a bad idea. Our request is to repair the issue cleanly. In the absence of any good reason in favor of FF BF BF, and given that FF C0 CB seems to be the standard IMHO, this translates to a request to change the RGB value of pink in xcolor (if we are afraid it could hurt, we could issue a warning to the log when pink is used) to (255/255, 192/255=0.752941176, 203/255=0.796078431) , i.e., 1,.752941176,.796078431, and adapt the other values (HSB, CMYK, gray) appropriately. Or, perhaps, we find an excellent argument for why the pink color should be (100%, 75%, 75%) in RGB and convince the Groff, X11, Wikipedia, HTML, and CSS communities to alter their definitions.

The xcolor maintainer from 2003-2021 has been informed.

Related: https://gitlab.freedesktop.org/xorg/app/rgb/-/issues/1 .