Converting Windows Paint RGB color model to xcolor's

Question

This question came up to me because I didn't want to define a new color in my LaTeX project.

I want to use a very specific color in my tikz drawing. Using Microsoft Paint's Color Picker tool, I get the following information about it:

The values I obtained with the tool are shown in the right window inside the screenshot, reading

Hue: 205
Saturation: 67
Lum(?) 123
Red: 165
Green: 96
Blue: 157

So I went over to TeX to try xcolor's color specification:

\documentclass[border=1pt]{standalone}
\usepackage{xcolor}
\begin{document}
\texttt{red!64.7!green!37.64!blue!61.56!} \hfill \fcolorbox{black}{red!64.7!green!37.64!blue!61.56!}{\hspace{2mm}}
\end{document}

(the red color is 165/255=64.7% so this the value I gave to red, same for green and blue).

Looks close, doesn't it?

So I headed over again to Windows Paint to see if color picker gives the same color, as in the first pick, and it turns out that no:

Hue: 169
Saturation: 95
Lum(brightness?) 148
Red: 136
Green: 119
Blue: 196

If I am not wrong, one can specifty a color using the rgb model, or the hue, saturation,brightness model. Both differ in the cross check I made.

How can I get exactly the same color?

Answer 1

To use a color by its RGB components directly in TikZ, see https://tex.stackexchange.com/a/343680/38080 and use for example:

\tikz \fill [color={rgb,255:red,165;green,95;blue,157}] (0,0) rectangle (1,1);

Alternatively, you can define a color or use a model directly: RGB is the model with red, blue, and green with range 0...255.

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\definecolor{mycolor}{RGB}{165,95,157}
\begin{document}
{\color{mycolor}\vrule width 50pt height 20pt}
(Back to black)
{\color[RGB]{165,95,157}\vrule width 50pt height 20pt}
(Now with Ti\emph{k}Z):
\tikz \fill [color={rgb,255:red,165;green,95;blue,157}] (0,0) rectangle (1,1);
\end{document}

Here is the result, with a bit of the color picker window:

You can find a list of color-changing command in section 2.6 of the manual:

Your ! command is a mix, used to blend colors; with

red!64.7!green!37.64!blue!61.56!

you are mixing 64.7% of red with green, then mix the 37.64% of the result with blue, and then mix the 61.56% of the result with white... See the manual at page 33 (thanks Steven B. Segletes! I got that the other way around) :

which is useful when you want to make gradients or color-coded thing, given that it works with whatever color, like mycolor1!50!mycolor2.