About the distance between the caption and the main body

Question

I found that there is too much space between the caption of the figure and the main body. (The caption is below the figure). I don't know how to reduce the distance among them? the code I use now is as follows,

\begin{figure}[htbp]
\begin{center}
\includegraphics[width=8cm]{./Fig/ransac.eps}
\end{center}
\vspace{-4mm}
\caption{An illustration of a pair of mismatched images.}
\label{2_RANSAC}
\end{figure}

Does anyone know how to solve this?

Answer 1

Two suggestions:

• Don't use the center environment to center a graph inside a figure environment. Use the instruction \centering instead. This will avoid inserting lots of unwanted vertical whitespace.

• Use the parameters \abovecaptionskip and \belowcaptionskip to set the distances between (a) the graph and the caption and (b) the caption and the "end" of the figure (or table) environment.

The following examples show the results of your original code, a modication that gets by without use of the center environment and without \vspace instructions, and a final modification that also shrinks the values of \abovecaptionskip and \belowcaptionskip, by 8 points each in the examples. The \hrule commands are there to outline the boundaries of the figure environments. I trust that these tools will let you find a setup that's to your liking.

\documentclass{article}
\usepackage[demo]{graphicx}
\begin{document}

original code:
\hrule
\begin{figure}[htbp]
\begin{center}
\includegraphics[width=8cm]{./Fig/ransac.eps}
\end{center}
\vspace{-4mm}
\caption{An illustration of a pair of mismatched images.}
\label{fig:1}
\end{figure}
\hrule

\bigskip
next try:
\hrule
\begin{figure}[htbp]
\centering
\includegraphics[width=8cm]{./Fig/ransac.eps}
\caption{An illustration of a pair of mismatched images.}
\label{fig:2}
\end{figure}
\hrule

\bigskip
\addtolength\abovecaptionskip{-8pt}
\addtolength\belowcaptionskip{-8pt}
final try:
\hrule
\begin{figure}[htbp]
\centering
\includegraphics[width=8cm]{./Fig/ransac.eps}
\caption{An illustration of a pair of mismatched images.}
\label{fig:3}
\end{figure}
\hrule
some text \emph{after} a ``figure'' environment
\end{document}