If you start by a sample image, in this case let's assume a gray square, then one possible solution is to insert that figure with a declared width of:
\includegraphics[width=\paperwidth,keepaspectratio]{Square.pdf}
inside a box with variable width:
\makebox[\linewidth]{%
\includegraphics[width=\paperwidth,keepaspectratio]{Immagine_Esempio.pdf}%
}
In this case the inserted parameter is not related to the portion of text by \textwidth
, but from the page (physical paper) itself by \paperwidth
.
So a complilable example with this figure Immagine_Esempio.pdf
with a caption, is as follows:
\documentclass{article}
%
\usepackage{graphicx}
%
\begin{document}
%
\begin{figure}[p]
\vspace*{-2cm} % space inserted to fit within the page number
\makebox[\linewidth]{%
\includegraphics[width=\paperwidth,keepaspectratio]{Immagine_Esempio.pdf}%
}
\caption{A caption}
\end{figure}
%
\end{document}
Gives for the output:
The parameter keepaspectratio
could be deactivated and set height=<>\textheight
and playing around \vspace*{<>}
for numbers in this case.