# Set different styles for “main” caption and description

I would like to redefine the \caption command to have to arguments : one "main" caption and then the description.

This is what I want :

 \begin{figure}
\caption{\textbf{Caption title} \newline \small{I would like this sentence to be under the title and smaller.}}
\end{figure}


Figure 1 - Caption title

I would like this sentence to be under the title and smaller.

But I want to change the format for all captions. I looked at the package caption :

\documentclass[10pt]{article}
\usepackage[french,english]{babel}
\usepackage[utf8]{inputenc}
\usepackage[margin=10pt,font=small,labelfont=bf,
labelsep=endash]{caption}

\newlength\myindention
\DeclareCaptionFormat{myformat}%
{#1#2\\\hspace*{\myindention}#3}
\setlength\myindention{1cm}
\captionsetup{format=myformat}

\begin{document}

\begin{figure}
\caption{Caption title. I would like this sentence to be under the title and smaller.}
\end{figure}

\end{document}


Figure 1

 Caption title. I would like this sentence to be under the title and smaller.


But only the title is above (which I expected, because I gave no indication about it - but I don't know how to change it).

I tried to add arguments in the formatting command :

    \DeclareCaptionFormat{myformat}%
{#1#2#3 \newline \small{#4}}

...
\caption{Caption title.}{I would like this sentence to be under the title and smaller}


But I get : "Illegal parameter number in definition of \caption"

Any help on that ?

• \newcommand\mycaption[2]{\caption{\textbf{#1}\newline\small#2}}? – Henri Menke May 30 '16 at 8:31
• Ow. It is my first time using \newcommand and I had missed the [2]. I did not think it was that simple. Thanks, it works perfectly. – Nausi May 30 '16 at 8:50
• a question for you ... do you want the full description in the table of contents? if not, there is nothing to prevent you from placing a block of text, separate from the caption, into a figure (or other float) environment. – barbara beeton May 30 '16 at 16:22
• True, I definitely don't want all the description in the ToC. I admit I had not thought about juste writing some text, which seems indeed to be the simplest solution... – Nausi May 31 '16 at 7:15

Instead of manipulation the original \caption command it might be easier to define a new command which handles the two arguments as intended.
\documentclass{article}