The 68 standard colors known to dvips

Invoke the package with the usenames and dvipsnames option. If you are using tikz or pstricks package you must declare the xcolor package before that, otherwise it will not work.

\usepackage[dvipsnames]{xcolor}

This above syntax may result in an error if you are using beamer with tikz. To go around it, include usenames and dvipsnames options when defining the document class.

\documentclass[usenames,dvipsnames]{beamer}

Place

Define the colors in the preamble of your document. (Reason: do so in the preamble, so that you can already refer to them in the preamble, which is useful, for instance, in an argument of another package that supports colors as arguments, such as the listings package.)

Method

You need to include the xcolor package in your preamble to define new colors. In the abstract, the colors are defined following this scheme:

\definecolor{name}{model}{color-spec}

where:

• name is the name of the color; you can call it as you like
• model is the way you describe the color, and is one of gray, rgb, RGB, HTML, and cmyk.
• color-spec is the description of the color

Color Models

Among the models you can use to describe the color are the following (several more are described in the xcolor manual):

Examples

To define a new color, follow the following example, which defines orange for you, by setting the red to the maximum, the green to one half (0.5), and the blue to the minimum:

\definecolor{orange}{rgb}{1,0.5,0}

The following code should give a similar results to the last code chunk.

\definecolor{orange}{RGB}{255,127,0}

If you loaded the xcolor package, you can define colors upon previously defined ones.

The first specifies 20 percent blue and 80 percent white; the second is a mixture of 20 percent blue and 80 percent black; and the last one is a mixture of (20*0.3) percent blue, ((100-20)*0.3) percent black and (100-30) percent green.

\color{blue!20}
\color{blue!20!black}
\color{blue!20!black!30!green}

xcolor also feature a handy command to define colors from color mixes:

\colorlet{notgreen}{blue!50!yellow}

Using color specifications directly

Normally one would predeclare all the colors as above, but sometimes it is convenient to directly use a color without naming it first. To achieve this, \color and \textcolor have an alternative syntax specifying the model in square brackets, and the color specification in curly braces. For example:

{\color[rgb]{1,0,0} This text will appear red-colored}
\textcolor[rgb]{0,1,0}{This text will appear green-colored}

Creating / Capturing colors

You may want to use colors that appear on another document, web pages, pictures, etc. Alternatively, you may want to play around with rgb values to create your own custom colors.

Image processing suites like the free GIMP suite for Linux/Windows/Mac offer color picker facilities to capture any color on your screen or synthesize colors directly from their respective rgb / hsv / hexadecimal values.

Smaller, free utilities also exist:

• Linux/BSD: The gcolor2 tool (usually also available in repositories)
• Microsoft Windows: The open-source Color Selector tool.
• Apple Macs: Hex Color Picker for creating custom colors and the built-in DigitalColor Meter for capturing colors on screen.
• Online utilities: See here for a Wikipedia article with several external links

Spot colors

Spot colors are customary in printing. They usually refer to pre-mixed inks based on a swatchbook (like Pantone, TruMatch or Toyo). The package colorspace extends xcolor to provide real spot colors (CMYK and CIELAB). They are defined with, say:

\definespotcolor{mygreen}{PANTONE 7716 C}{.83, 0, .40, .11}