How to define a CMYK color using values between 0 and 255

Question

I would like to define my own CMYK colors in LaTeX. I know that it can be done with the

\definecolor{my_color_name}{cmyk}{c,y,m,k}

command, but here, values between 0and 1 are used. The problem is that I have a color map available that gives me all colors in CMYK with values from 0 to 255 and I don't want to divide all values by 255 manually. For defining RGB-colors, LaTeX provides the commands

\definecolor{my_color_name}{rgb}{r,g,b}
\definecolor{my_color_name}{RGB}{R,G,B}

where {r,g,b} between 0 and 1 and {R,G,B} between 0 and 255. Therefore, I am looking for something similar for the CMYK scheme. Any ideas?

Answer 1

I don't know how you receive your data, but this may give you an idea of how to proceed:

\documentclass{article}

\usepackage{xcolor}
\usepackage{tikz}

\newcommand{\hexcmyk}[5]{%
    \pgfmathsetmacro{\myc}{#1/255}%
    \pgfmathsetmacro{\mym}{#2/255}%
    \pgfmathsetmacro{\myy}{#3/255}%
    \pgfmathsetmacro{\myk}{#4/255}%
    \definecolor{testcolor}{cmyk}{\myc,\mym,\myy,\myk}%
    \textcolor{testcolor}{#5}% Trivial application
}

\def\hhexcmyk(#1,#2,#3,#4)#5{%
    \pgfmathsetmacro{\myc}{#1/255}%
    \pgfmathsetmacro{\mym}{#2/255}%
    \pgfmathsetmacro{\myy}{#3/255}%
    \pgfmathsetmacro{\myk}{#4/255}%
    \definecolor{testcolor}{cmyk}{\myc,\mym,\myy,\myk}%
    \textcolor{testcolor}{#5}% Trivial application
}

\def\defineCMYKcolor(#1,#2,#3,#4)#5{%
    \pgfmathsetmacro{\myc}{#1/255}%
    \pgfmathsetmacro{\mym}{#2/255}%
    \pgfmathsetmacro{\myy}{#3/255}%
    \pgfmathsetmacro{\myk}{#4/255}%
    \definecolor{#5}{cmyk}{\myc,\mym,\myy,\myk}%
}

\defineCMYKcolor(155,0,255,10){mygreen}

\begin{document}

\hexcmyk{0}{255}{255}{0}{Test text.}

\hhexcmyk(255,0,255,0){TEST}

\defineCMYKcolor(0,255,155,10){myred}

\textcolor{myred}{This is some more text.}

\textcolor{mygreen}{This yet more text.}

\end{document}

Produces this:

It occurred to me that I don't know how the data are presented so expanded my answer to give another solution to the problem.

Answer 2

With only the need of package xcolor:

\usepackage{xcolor}

{\lccode`\?=`\p \lccode`\!=`\t  \lowercase{\gdef\ignorept#1?!{#1}}}
\def\divbyccvv#1{\expandafter\ignorept\the\dimexpr#1pt/255\relax}

\def\defineCMYKcolor#1#2{\defineCMYKcolorA{#1}#2,} 
\def\defineCMYKcolorA#1#2,#3,#4,#5,{\edef\tmp{\noexpand\definecolor{#1}{cmyk}%
      {\divbyccvv{#2},\divbyccvv{#3},\divbyccvv{#4},\divbyccvv{#5}}}\tmp
}

\defineCMYKcolor{my_color_name}{255,0,50,11}

\begin{document}
    \color{my_color_name}test in my_color
\end{document}

Answer 3

Use the facilities of xparse and expl3:

\documentclass{article}
\usepackage{xcolor}
\usepackage{xparse}

\ExplSyntaxOn
\NewDocumentCommand{\defineCMYKcolor}{mm}
 {
  \tceighteight_define_CMYK_color:nn { #1 } { #2 }
 }

\seq_new:N \l_tceighteight_input_seq
\seq_new:N \l_tceighteight_output_seq

\cs_new_protected:Npn \tceighteight_define_CMYK_color:nn #1 #2
 {
  % split the input into parts
  \seq_set_split:Nnn \l_tceighteight_input_seq { , } { #2 }
  % convert each item to a decimal value in [0,1]
  \seq_set_map:NNn \l_tceighteight_output_seq  \l_tceighteight_input_seq
   {
    \fp_eval:n { ##1/255 }
   }
  % now define the color
  \definecolor{#1}{cmyk}{ \seq_use:Nn \l_tceighteight_output_seq { , } }
 }
\ExplSyntaxOff

\defineCMYKcolor{test}{32,100,211,99}

\begin{document}

\textcolor{test}{ABCDEF}

\end{document}

The four numbers are stored in a sequence (one might add here some sanity checks) and then transformed into another sequence that is used in the appropriate \definecolor command.

If I ask what the color test expands to, I get

> \\color@test=macro:
->\xcolor@ {}{0.12549 0.39215 0.82745 0.38823 k 0.12549 0.39215 0.82745 0.38823
 K}{cmyk}{0.12549,0.39215,0.82745,0.38823}.

and, for checking the values, I multiplied them back by 255, getting

0.12549*255 = 31.99995
0.39215*255 = 99.99825
0.82745*255 = 210.99975
0.38823*255 = 98.99865

which seems good (some small error is expected anyway).