Justify a text inside a figure environment
You can use \caption* from the caption package to add additional text; using \captionsetup you can customize the formatting:
\documentclass[11pt]{scrartcl}
\usepackage{caption}
\usepackage{lipsum}% just to generate text for the example
\begin{document}
\begin{figure}
\centering
\caption{test}
\captionsetup{singlelinecheck=off,font=footnotesize}
\caption*{Some additional text}
\rule{2cm}{2cm}% to simulate an actual figure
\end{figure}
\lipsum[2]
\end{document}
What's the problem with the following? Just issue \centering when needed.
\documentclass{article}
\usepackage[demo]{graphicx} % demo is for the example
\usepackage{lipsum} % to provide some text
\begin{document}
\begin{figure}
\caption{NICE TITLE}\label{graph:p}
\medskip
\lipsum[2]
\medskip
\centering
\includegraphics[width=0.8\textwidth]{FIG.png}
\end{figure}
\end{document}
Another option is to use the floatrow package and its \floatfoot macro. The additional text will be justified by default, and there's no need to add extra commands like \medskip or \captionsetup within individual floats.
\documentclass{article}
\usepackage{caption}
\usepackage{floatrow}
\floatsetup[figure]{capposition=top,footposition=caption}
\captionsetup[figure]{footfont=small}
\usepackage{lipsum}
\begin{document}
\begin{figure}
\rule{1cm}{1cm}
\caption{A figure}
\floatfoot{\lipsum[1]}
\end{figure}
\end{document}
