With multiple images in one figure, why is the last image spaced differently?

Question

I have a figure with eight images of the same size. They fit two to a row and the first three rows look great, but the fourth row gets weird; where the first three have their images spaced apart left-to-right, the final row has them left-aligned next to each other without a gap.

My original code is below with eight images scaled to 25%, however I've tried it with:

• Eight images scaled to 20%
• Six images scaled to 25%
• Six images scaled to 20%

And seen the same behavior each time -- the last image is always aligned differently.

Code:

\begin{figure}[h]
    \caption{2.68 logic tests}
    \includegraphics[scale=.25]{3x8_decoder_0}
    \includegraphics[scale=.25]{3x8_decoder_1}
    \includegraphics[scale=.25]{3x8_decoder_2}
    \includegraphics[scale=.25]{3x8_decoder_3}
    \includegraphics[scale=.25]{3x8_decoder_4}
    \includegraphics[scale=.25]{3x8_decoder_5}
    \includegraphics[scale=.25]{3x8_decoder_6}
    \includegraphics[scale=.25]{3x8_decoder_7}
    \label{fig:3x8proof}
\end{figure}

Example of the original problem:

Answer 1

The line breaks are currently falling serendipitously but randomly after every second picture. To make the intended look more explicit, you could write

\begin{figure}[h]
\caption{2.68 logic tests} \label{fig:3x8proof}

    \includegraphics[scale=.25]{3x8_decoder_0}\hfill
    \includegraphics[scale=.25]{3x8_decoder_1}

    \includegraphics[scale=.25]{3x8_decoder_2}\hfill
    \includegraphics[scale=.25]{3x8_decoder_3}

    \includegraphics[scale=.25]{3x8_decoder_4}\hfill
    \includegraphics[scale=.25]{3x8_decoder_5}

    \includegraphics[scale=.25]{3x8_decoder_6}\hfill
    \includegraphics[scale=.25]{3x8_decoder_7}  
\end{figure}

The blank lines will force line breaks, and the \hfill instructions will space the graphs maximally apart.

Answer 2

Can't tell you why, but I can help you out with a workaround.

\begin{figure}[h]
    \caption{2.68 logic tests} \label{fig:3x8proof}
    \begin{minipage}{.5\textwidth}
        \includegraphics[scale=.25]{3x8_decoder_0}\\
        \includegraphics[scale=.25]{3x8_decoder_2}\\
        \includegraphics[scale=.25]{3x8_decoder_4}\\
        \includegraphics[scale=.25]{3x8_decoder_6}
    \end{minipage}%
    \begin{minipage}{.5\textwidth}
        \begin{flushright}
            \includegraphics[scale=.25]{3x8_decoder_1}\\
            \includegraphics[scale=.25]{3x8_decoder_3}\\
            \includegraphics[scale=.25]{3x8_decoder_5}\\
            \includegraphics[scale=.25]{3x8_decoder_7}
        \end{flushright}
    \end{minipage}
\end{figure}

Don't forget that \textwidth inside of the minipage is based on the size of the minipage So in this case .5 inside the minipage would correspond to .25 of the entire sites textwidth.

Just a little fix to workaround the \textwidth + eps figure, which would be wider than actual \textwidth.