How to remove numbering from one single entry in list of figures

Question

I have multiple figures, and I have one specific figure for which I would like to remove the numbering in the \listoffigures, let us call it fig_x

I have found on other threads that using the caption package allows for the inclusion of \captionsetup{labelformat=empty}, but this only removes the caption number from the body of the document; in the list of figures however, the figure number is still displayed.

Are there any alternatives so as to remove the figure number from the lof?

\documentclass[oneside, a4paper, 12pt]{book}
\usepackage{booktabs}
\usepackage{graphicx}
\usepackage{caption} % < caption package


\begin{document}
\frontmatter
\listoffigures % <<< my list of figures
\chapter{General Introduction}

\mainmatter
\chapter{CH1}
Some text here, figure:

\begin{figure}
\captionsetup{labelformat=empty} % <<< removes fig numb. from the caption; does not remove from lof
\caption{Diagram of Preemptive Dialogic Model}\vspace{5mm}
\includegraphics{fig_x}
\label{fig_x}
\end{figure}

\backmatter
\tableofcontents

\end{document}

Answer 1

Use \caption*{ ...} to remove it from the LoF and add a line to the LoF with the caption text without the figure number: \addcontentsline{lof}{figure}{<text>}.

The figure "b" is listed without number.

while all figures are displayed.

\documentclass[oneside, a4paper, 12pt]{book}
\usepackage{shorttoc}
\usepackage{times}
\usepackage{titlesec}
\usepackage{anyfontsize}
\usepackage[french]{babel}
\usepackage{booktabs}
\usepackage{sectsty}
%\usepackage{arabtex}
\usepackage{caption}
%\usepackage{utf8}
\usepackage{enumerate}
%\setcode{utf8}

\usepackage{graphicx}


\begin{document}
    \frontmatter
    \listoffigures % <<< my list of figures
    \chapter{General Introduction}
    
    \mainmatter
    \chapter{CH1}
    Some text here, figure:
    
        \begin{figure}[htp!]        
        \captionsetup{labelformat=empty} % <<< removes fig numb. from the caption; does not remove from lof
        \caption{Diagram of Preemptive Dialogic Model a}\vspace{5mm}
        \includegraphics{example-image-a}
        \label{fig_x1}
    \end{figure}
    
    
    
    \begin{figure}[htp!]
        \captionsetup{labelformat=empty} % <<< removes fig numb. from the caption; does not remove from lof
        \caption*{Diagram of Preemptive Dialogic Model b} % without number and not in LoF
        \addcontentsline{lof}{figure}{Diagram of Preemptive Dialogic Model b} % add to LoF without numbering
        \vspace{5mm}
        \includegraphics{example-image-b}
        \label{fig_x2}
    \end{figure}

    \begin{figure}[htp!]        
    \captionsetup{labelformat=empty} % <<< removes fig numb. from the caption; does not remove from lof
    \caption{Diagram of Preemptive Dialogic Model c}\vspace{5mm}
    \includegraphics{example-image-c}
    \label{fig_x3}
    \end{figure}
        
    \backmatter
    \tableofcontents
    
\end{document}