IEEE trans: Cite subfigure reference

Question

I have a figure that contains four subfigures with captions and I want to cite the subfigure. I tried a lot but it didn't work out. Below is not working

\usepackage{subfigure}
Some text \subref{fig:multi-scale} Figure \ref{fig:overall_figure}

COMPLETE LATEX CODE

%%%% ijcai21.tex
\typeout{IJCAI--21 Instructions for Authors}
% These are the instructions for authors for IJCAI-21.
\documentclass{IEEEtran}
% Use the postscript times font!
\usepackage{times}
\usepackage{soul}
\usepackage{url}
%\usepackage[hidelinks]
%\usepackage[utf8]{inputenc}
%\usepackage[small]{caption}
%\usepackage{graphicx}
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{booktabs}
\usepackage{algorithm}
\usepackage{algorithmic}
\urlstyle{same}
\usepackage[table,xcdraw]{xcolor}
\usepackage{comment}
\usepackage{multirow}
\usepackage{amsfonts}
\usepackage{makecell}
\usepackage[colorlinks=true,linkcolor=blue]{hyperref}%
%\usepackage{subfigure}
%\usepackage{caption}
%\usepackage{subfig}
\usepackage{graphicx}
\usepackage[caption=false]{subfig}
%\usepackage{cleveref}
% You need a newsubfloat element to use subcaption
\definecolor{mygray}{gray}{.92}
% thickline==============================================================================
\makeatletter
\def\thickhline{%
  \noalign{\ifnum0=}\fi\hrule \@height \thickarrayrulewidth \futurelet \reserved@a\@xthickhline} \def\@xthickhline{\ifx\reserved@a\thickhline \vskip\doublerulesep \vskip-\thickarrayrulewidth \fi \ifnum0={\fi}}
\makeatother
\newlength{\thickarrayrulewidth}
\setlength{\thickarrayrulewidth}{2\arrayrulewidth}
%======================================================================================
\title{Deep Learning}
\author{
Anonymous Author
\thanks{A. A is with the Department
of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta,
GA, 30332}% <-this % stops a space
\thanks{Anonymous and Anonymous are with Anonymous University.}% <-this % stops a space
\thanks{Manuscript Submission April 19, 2022; revised August 00, 0000.}}
\begin{document}
\maketitle
\begin{abstract}
  xxx
\end{abstract}
%
\begin{figure}[!t]
    \subfloat[Deep Residual Auto-Encoder]{\includegraphics[width=3cm]{cat.jpg}}
    \label{fig:deep_residual}
    \vspace{10pt}
    \subfloat[Multi-scale network]{\includegraphics[width=3cm]{cat.jpg}}
    \label{fig:multi-scale}
    \caption{Oversimplified view of single iterative networks for image compression}
    \label{fig:overall_figure}
\end{figure}
Cross references: \subref{fig:deep_residual}
and \subref{fig:multi-scale} of \ref{fig:overall_figure}
\small
\bibliographystyle{IEEEtran}
\bibliography{ijcai21}
\end{document}

Answer 1

The package subfigure has been obsolete and deprecated for several years. Its author provided the successor package subfig.

There is also a superior package called subcaption, but it is not compatible with IEEEtran:

Package caption Warning: Unknown document class (or package),
(caption)                standard defaults will be used.
See the caption package documentation for explanation.

The warning you get upon loading subcaption in a IEEEtran document means that captions will be overridden and this won't please the copy editor to whom you submit your article.

Solution: use subfig.

\documentclass{IEEEtran}
\usepackage{graphicx}
\usepackage[caption=false]{subfig}
\usepackage{lipsum} % for mock text
\begin{document}
Cross references: \subref{fig:gdn_network}
and \subref{fig:multi_layer} of \ref{fig:overall_figure}
\lipsum
\begin{figure}[!t]
\centering
\subfloat[%
  GDN Network \cite{balle2016end}\label{fig:gdn_network}%
]{\includegraphics[width=3cm]{example-image}}
\subfloat[%
  Multi-layer GDN Network \cite{balle2017end}\label{fig:multi_layer}%
]{\includegraphics[width=3cm]{example-image}}
\caption{Global caption in the style IEEEtran defines\label{fig:overall_figure}}
\end{figure}
\lipsum[2-12]
\end{document}

Answer 2

Using the caption and subcaption packages you can define \label inside them.

The MWE follows:

\documentclass{article}
\usepackage{graphicx}
\usepackage{caption,subcaption}
\captionsetup{justification=centering}
\captionsetup[figure]{position=below}
\captionsetup[subfigure]{position=below}
\usepackage[colorlinks]{hyperref}
\begin{document}
\ref{fig:many_figures}, \autoref{fig:many_figures}. \ref{fig:gdn_network}, \autoref{fig:gdn_network}. \ref{fig:multi_layer}, \autoref{fig:multi_layer}.
\begin{figure}[!ht]
  \centering
  \caption{Many figures}
  \label{fig:many_figures}
  \subcaption{GDN Network\cite{balle2016end}}{\includegraphics[width=0.4\textwidth]{example-image}}
  \vspace{10pt}
  \label{fig:gdn_network}
  \subcaption{Multi-layer GDN Network \cite{balle2017end}}{\includegraphics[width=0.4\textwidth]{example-image-a}}
  \label{fig:multi_layer}
\end{figure}
\ref{fig:fig_name}, \autoref{fig:fig_name}. \ref{subfig:fig_name-a}, \autoref{subfig:fig_name-a}. \ref{subfig:fig_name-b}, \autoref{subfig:fig_name-b}.
\begin{figure}[!ht]
  \centering
  \captionbox{Legend figure\label{fig:fig_name}}[\linewidth]{
    \subcaptionbox{Legend a\label{subfig:fig_name-a}}{
      \includegraphics[width=.2\linewidth]{example-image-a}
    };
    \subcaptionbox{Legend b\label{subfig:fig_name-b}}{
      \includegraphics[width=.2\linewidth]{example-image-b}
    }
  }
\end{figure}
\begin{thebibliography}{1}
  \bibitem{balle2016end}
  Balle 2016 Reference text
\bibitem{balle2017end}
  Balle 2017 Reference text
\end{thebibliography}
\end{document}