Como adicionar legendas adicionais ao lado esquerdo de cada linha?

Question

Estou tentando adicionar legendas extras no topo da primeira linha e à esquerda de cada linha, e não sei como adicioná-las ao lado esquerdo de cada linha. Este é o código que tentei:

\documentclass{article}
\usepackage{graphicx}
\usepackage{subcaption}

\begin{document}

\begin{figure}
    \begin{subfigure}{0.18\linewidth}
        \centering
        \caption*{Caption for Figure 1}
        \label{fig:sub1}
        \includegraphics[width=\linewidth]{example-image}
    \end{subfigure}%
    \hspace{5pt}%
    \begin{subfigure}{0.18\linewidth}
        \centering
        \caption*{Caption for Figure 2}
        \label{fig:sub2}
        \includegraphics[width=\linewidth]{example-image}
    \end{subfigure}%
    \hspace{5pt}%
    \begin{subfigure}{0.18\linewidth}
        \centering
        \caption*{Caption for Figure 3}
        \label{fig:sub3}
        \includegraphics[width=\linewidth]{example-image}
    \end{subfigure}%
    \hspace{5pt}%
    \begin{subfigure}{0.18\linewidth}
        \centering
        \caption*{Caption for Figure 4}
        \label{fig:sub4}
        \includegraphics[width=\linewidth]{example-image}
    \end{subfigure}%
    \hspace{5pt}%
    \begin{subfigure}{0.18\linewidth}
        \centering
        \caption*{Caption for Figure 5}
        \label{fig:sub5}
        \includegraphics[width=\linewidth]{example-image}
    \end{subfigure}

    \vspace{10pt} % Add vertical space between the rows

    \begin{subfigure}{0.18\linewidth}
        \centering
        \includegraphics[width=\linewidth]{example-image}
    \end{subfigure}%
    \hspace{5pt}%
    \begin{subfigure}{0.18\linewidth}
        \centering
        \includegraphics[width=\linewidth]{example-image}
    \end{subfigure}%
    \hspace{5pt}%
    \begin{subfigure}{0.18\linewidth}
        \centering
        \includegraphics[width=\linewidth]{example-image}
    \end{subfigure}%
    \hspace{5pt}%
    \begin{subfigure}{0.18\linewidth}
        \centering
        \includegraphics[width=\linewidth]{example-image}
    \end{subfigure}%
    \hspace{5pt}%
    \begin{subfigure}{0.18\linewidth}
        \centering
        \includegraphics[width=\linewidth]{example-image}
    \end{subfigure}

    \caption{Caption}
    \label{fig:main}
\end{figure}

\end{document}

Esta é a saída do código:

É isso que eu quero:

Answer 1

Também fiz algumas alterações gratuitas de formatação. Observe que \labelnão funciona com \caption*.

\documentclass{article}
\usepackage{subcaption}
\usepackage[export]{adjustbox}% for valign
\usepackage{graphicx}
\usepackage{showframe}% alignment tool

\begin{document}

\begin{figure}
    \centering
    \captionsetup[subfigure]{justification=raggedright}
    \begin{subfigure}{0.15\linewidth}
      \caption*{Caption 1}
    \end{subfigure}\hfil
    \begin{subfigure}{0.15\linewidth}
        \caption*{Caption for Figure 1}
        \includegraphics[width=\linewidth, valign=c]{example-image}
    \end{subfigure}\hfil
    \begin{subfigure}{0.15\linewidth}
        \caption*{Caption for Figure 2}
        \includegraphics[width=\linewidth, valign=c]{example-image}
    \end{subfigure}\hfil
    \begin{subfigure}{0.15\linewidth}
        \caption*{Caption for Figure 3}
        \includegraphics[width=\linewidth, valign=c]{example-image}
    \end{subfigure}\hfil
    \begin{subfigure}{0.15\linewidth}
        \caption*{Caption for Figure 4}
        \includegraphics[width=\linewidth, valign=c]{example-image}
    \end{subfigure}\hfil
    \begin{subfigure}{0.15\linewidth}
        \caption*{Caption for Figure 5}
        \includegraphics[width=\linewidth, valign=c]{example-image}
    \end{subfigure}

    \vspace{\floatsep} % Add vertical space between the rows

    \begin{subfigure}{0.15\linewidth}
      \caption*{Caption 2}
    \end{subfigure}\hfil
    \begin{subfigure}{0.15\linewidth}
        \includegraphics[width=\linewidth, valign=c]{example-image}
    \end{subfigure}\hfil
    \begin{subfigure}{0.15\linewidth}
        \includegraphics[width=\linewidth, valign=c]{example-image}
    \end{subfigure}\hfil
    \begin{subfigure}{0.15\linewidth}
        \includegraphics[width=\linewidth, valign=c]{example-image}
    \end{subfigure}\hfil
    \begin{subfigure}{0.15\linewidth}
        \includegraphics[width=\linewidth, valign=c]{example-image}
    \end{subfigure}\hfil
    \begin{subfigure}{0.15\linewidth}
        \includegraphics[width=\linewidth, valign=c]{example-image}
    \end{subfigure}

    \caption{Caption}
    \label{fig:main}
\end{figure}

\end{document}

---

Esta solução usa um arquivo tabular. Embora isso exija computação \tabcolsep, o resultado é mais simples que a versão tabular*.

\documentclass{article}
\usepackage{array}
\usepackage{graphicx}
\usepackage{showframe}% alignment tool

\begin{document}

\begin{figure}
    \centering
    \setlength{\tabcolsep}{\dimexpr 0.1\textwidth/12}% 6*0.15=0.9
    \begin{tabular}{*6{m{0.15\textwidth}}}
      & {\raggedright Caption for Figure 1}
      & {\raggedright Caption for Figure 2}
      & {\raggedright Caption for Figure 3}
      & {\raggedright Caption for Figure 4}
      & {\raggedright Caption for Figure 5}
    \\[\abovecaptionskip]
      {\hfil Caption 1} 
      & \includegraphics[width=\linewidth]{example-image}
      & \includegraphics[width=\linewidth]{example-image}
      & \includegraphics[width=\linewidth]{example-image}
      & \includegraphics[width=\linewidth]{example-image}
      & \includegraphics[width=\linewidth]{example-image}
    \\[\floatsep]
      {\hfil Caption 2}
      & \includegraphics[width=\linewidth]{example-image}
      & \includegraphics[width=\linewidth]{example-image}
      & \includegraphics[width=\linewidth]{example-image}
      & \includegraphics[width=\linewidth]{example-image}
      & \includegraphics[width=\linewidth]{example-image}
    \end{tabular}
    \caption{Caption}
    \label{fig:main}
\end{figure}

\end{document}