[Tex/LaTex] how to use labels in subfloat

subfloats

\begin{figure}%
    \centering
    \subfloat[Original]{{\includegraphics[width=4cm]{cata_orig.png} }}%
    \qquad
    \subfloat[Imposter]{{\includegraphics[width=4cm]{cata_impos.png} }}%
    \caption{Catalog Images}%
    \label{fig:cata}%
\end{figure}

In my latex file, when I do Fig. \ref{fig:cata} it compiles it to Fig. 4. But how do I refer cata_orig.png which is labeled (a) in compiling. 

\begin{figure}%
    \centering
    \subfloat[Original]{{\includegraphics[width=4cm]{cata_orig.png} \label{fig:hello}}%
    \qquad
    \subfloat[Imposter]{{\includegraphics[width=4cm]{cata_impos.png} }}%
    \caption{Catalog Images}%
    \label{fig:cata}%
\end{figure}

I added a \label{} in the subfloat but when I try to refer it using \protect\subref{fig:hello}, it compiles to (a). I want it to say 4 (a).

Best Answer

Update: A modern version (replacing subfig by the more modern subcaption):

image

\documentclass{article}

\usepackage[demo]{graphicx}
\usepackage{subcaption}

\begin{document}
\begin{figure}%
    \centering
    \begin{subfigure}{4cm}
    \includegraphics[width=\linewidth]{cata_orig.png}
    \caption{Original}\label{fig:orig}
    \end{subfigure}
    \qquad
    \begin{subfigure}{4cm}
    \includegraphics[width=4cm]{cata_impos.png}
    \caption{Imposter}
    \end{subfigure}
    \caption{Catalog Images}%
    \label{fig:cata}%
\end{figure}
\ref{fig:orig}
\end{document}

Here's one option (adding the reference to the caption):

image

\documentclass{article}

\usepackage[demo]{graphicx}
\usepackage{subfig}

\begin{document}
\begin{figure}%
    \centering
    \subfloat[Original\label{fig:orig}]{{\includegraphics[width=4cm]{cata_orig.png} }}%
    \qquad
    \subfloat[Imposter]{{\includegraphics[width=4cm]{cata_impos.png} }}%
    \caption{Catalog Images}%
    \label{fig:cata}%
\end{figure}
\ref{fig:orig}
\end{document}
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