How can I automatically center an image?

Question

I use:

\documentclss{mwrep}
...
\begin{figure}  
\includegraphics{a.jpg}
\caption[Long caption]{Caption}
\label{pic-a}
\end{figure}

How can I make images to be always visible on the center of page? (To be more specific: the center of the image should be between the left and right margin - I use different left and right margins). I don't want to put anything after every \begin{figure} in my document.

Important: I don't want to waste an entire page on a single image at the very center of the page. I want only horizontal alignment. (left <-> right)

Answer 1

With regard to your first question: Use the floatrow package -- it centers the content of floats by default.

\documentclass{article}

\usepackage[draft]{graphicx}
\usepackage{floatrow}

\begin{document}

The first paragraph.

\begin{figure}  
\includegraphics{a.jpg}
\caption[Long caption]{Caption}
\label{pic-a}
\end{figure}

And the second.

\end{document}

If you don't want to load floatrow for whatever reason, you may instead add the following to your preamble (thanks to egreg for the tip):

\makeatletter
\g@addto@macro\@floatboxreset\centering
\makeatother

EDIT: The figure in my example only was vertically centered because I had not added any dummy text. Example corrected.

Answer 2

Add the following to your document preamble:

\makeatletter
\g@addto@macro\@floatboxreset{\centering}
\makeatother

The start of every float construction ends with a macro \@floatboxreset that looks like this (from latex.ltx):

\def \@floatboxreset {%
        \reset@font
        \normalsize
        \@setminipage
}

Executing the above suggestion adds \centering at the end of \@floatboxreset, effectively changing it to

\def \@floatboxreset {%
        \reset@font
        \normalsize
        \@setminipage
        \centering
}

which removes the requirement to specify \centering all the time.

Answer 3

If you're using the memoir documentclass, global float adjustment may be set using: \setfloatadjustment{<float>}{<adjustment>}. For example,

\documentclass{memoir}
\setfloatadjustment{figure}{\centering}
\begin{document}
  \begin{figure}  
    \includegraphics{image}
    \caption[LoF caption]{Regular caption}
    \label{fig:image}
  \end{figure}
\end{document}

Answer 4

You could redefine the figure environment to include the \centering command:

\let\origfigure\figure
\let\endorigfigure\endfigure

\renewenvironment{figure}[1][tbph]{%
    \origfigure[#1]%
    \centering
}{%
    \endorigfigure
}

Answer 5

Another way to center all images, is to use \adjincludegraphics from the adjustbox package and declare the center to be used for all of them after any local options. However, this will add center also to all other \adjustbox macros and adjustbox environments. I actually just like to show the principle:

\documentclass{article}

\usepackage{lipsum}% for fummy text only
\usepackage[draft]{graphicx}% remove 'draft' for a real document
\usepackage{adjustbox}
\adjustboxset*{center}
\begin{document}

\lipsum[1]

\begin{figure}
\adjincludegraphics[width=5cm]{a.jpg}
\caption[Long caption]{Caption}
\label{pic-a}
\end{figure}

\lipsum[2]

\begin{figure}
\adjincludegraphics{b.jpg}
\caption[Long caption]{Caption}
\label{pic-b}
\end{figure}

\lipsum[3]

\begin{figure}
\adjincludegraphics{c.jpg}
\caption[Long caption]{Caption}
\label{pic-c}
\end{figure}


\end{document}