how to use subfigimg macro and \label

Question

I'm using the macro subfigimg provided in this post and it is working great. My problem however is that I would like to \ref to one of the subfigures (which use subfigimg macro) and i have no idea how to do it.

To give an exemple, I would like to do something like that:

\documentclass{revtex4-1} % http://ctan.org/pkg/ltxutil
\usepackage{graphicx} % http://ctan.org/pkg/graphicx
\newcommand{\subfigimg}[3][,]{%
  \setbox1=\hbox{\includegraphics[#1]{#3}}% Store image in box
  \leavevmode\rlap{\usebox1}% Print image
  \rlap{\hspace*{10pt}\raisebox{\dimexpr\ht1-2\baselineskip}{#2}}% Print label
  \phantom{\usebox1}% Insert appropriate spcing
}
\begin{document}
\begin{figure}[H]
  \centering
  \begin{tabular}{p{0.5\linewidth}@{}p{0.5\linewidth}}
     \subfigimg[width=\linewidth]{(a)}{example-image-a}
     \label{fig:1} &
     \subfigimg[width=\linewidth]{(b)}{example-image-b}
     \label{fig:2}
  \end{tabular}
  \caption{bla bla bla}
\end{figure}
\end{document}

Which of course does not work and result in ?? instead of a number. is there a way to work around it? or add option to label in the macro?

I'm really new to tex and to this forum, so please forgive me for being a noob and if I made any mistake.

thanks, liron

Answer 1

I build something that is a) a complete MWE and b) does what you want.

Now the labels are displayed like "1.a" and the letters are changed to small letters. If you want to change the formatting of the subfigimg labels change the \renewcommand*{\thesubfigs} to your liking, note that this only changes the way the labels are displayed, not those inside the images, for that change the \alph{subfigs} in the definition of \@subfigimg.

The command \subfigimg is available as a starred and an unstarred version. Use the starred version if you use \caption in the figure environment prior to your \subfigimg and the unstarred one else. This is necessary because we have to increase the c@figure-counter temporarily in order to get correct labels if the \caption is used after \subfigimg.

If you don't need a label on a \subfigimg just leave the last argument empty.

I added the possibility to change the position of the label with two additional arguments. They are to be inserted in between the 2 mandatory arguments. The first is inserted with <horizontal> (so <> as delimiters) and changes the horizontal offset, the second [vertical] changes the vertical offset.

\documentclass[preview,border=4mm]{standalone}

\usepackage{graphicx}
\usepackage{xparse}

\newcounter{subfigs}[figure]
\renewcommand*{\thesubfigs}{\thefigure.\alph{subfigs}}

\makeatletter
\NewDocumentCommand{\subfigimg}{s O{} m D<>{10pt} O{2\baselineskip} m}{%
    \IfBooleanTF{#1}%
        {\@subfigimg{#2}{#3}{#6}{0}{#4}{#5}}%
        {\@subfigimg{#2}{#3}{#6}{1}{#4}{#5}}%
}
\newcommand*{\@subfigimg}[6]{%
  \bgroup%
  \advance\c@figure by #4%
  \refstepcounter{subfigs}%
  \ifx\relax#3\relax\else%
  \label{#3}%
  \fi%
  \setbox1=\hbox{\includegraphics[#1]{#2}}% Store image in box
  \leavevmode\rlap{\usebox1}% Print image
  \rlap{\hspace*{#5}\raisebox{\dimexpr\ht1-#6\relax}{(\alph{subfigs})}}% Print label
  \phantom{\usebox1}% Insert appropriate spcing
  \egroup%
}

\makeatother

\begin{document}
\begin{figure}
  \centering
  \begin{tabular}{p{0.5\linewidth}@{}p{0.5\linewidth}}
     \subfigimg[width=\linewidth]{example-image-c}{fig:s11}
      &
     \subfigimg[width=\linewidth]{example-image-b}{fig:s12}
  \end{tabular}
  \caption{bla bla bla}
  \label{fig:1}
\end{figure}
See subfigures \ref{fig:s11} and \ref{fig:s12} of figure~\ref{fig:1}
\begin{figure}
  \centering
  \caption{bla bla bla}
  \label{fig:2}
  \begin{tabular}{p{0.5\linewidth}@{}p{0.5\linewidth}}
     \subfigimg*[width=\linewidth]{example-image-c}<20pt>[4\baselineskip]{fig:s21}
      &
     \subfigimg*[width=\linewidth]{example-image-b}{fig:s22}
  \end{tabular}
\end{figure}
See subfigures \ref{fig:s21} and \ref{fig:s22} of figure~\ref{fig:2}
\end{document}

Note that the subfigs counter is only reset after the figure counter is increased or when you manually reset it with something like \setcounter{subfigs}{0}.

Answer 2

Here's a solution that employs the widely-used subcaption package, which provides LaTeX environments called subfigure and subtable. The package also provides lots of options for configuring the formats of all captions.

\documentclass{revtex4-1}
\usepackage{graphicx,subcaption} 
\makeatletter
\renewcommand{\p@subfigure}{\thefigure.} % note the '.'
\makeatletter

\begin{document}

\begin{figure}

\begin{subfigure}{0.475\textwidth}
\includegraphics[width=\linewidth]{example-image-a}
\caption{First subfigure}\label{fig:small_a}
\end{subfigure}\hfill
\begin{subfigure}{0.475\textwidth}
\includegraphics[width=\linewidth]{example-image-b}
\caption{Second subfigure}\label{fig:small_b}
\end{subfigure}

\caption{bla bla bla} \label{fig:big}
\end{figure}

\noindent
Some cross-references to Figure \ref{fig:big} and to Subfigures \ref{fig:small_a} and \ref{fig:small_b}.
\end{document}