I am looking for a way to center images independent of the predefined border margins. As you can see, image A is centered relative to the text. B is somthing wrong completly or in other words does not ignore the text-margin. C is a try but I would like to auto center the image (even overlapping the margin text). Thanks in Advance.
\documentclass[twoside]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[ngerman]{babel}
\usepackage[paperheight=28cm, paperwidth=14cm,%
top=2cm, bottom=2cm, left=1cm, right=2.5cm,%
]{geometry}
\usepackage{xcolor}
\usepackage{scrlayer}
\usepackage{lmodern}
\usepackage{graphicx}
\usepackage{longtable}
\usepackage{pdfpages}
\usepackage{blindtext}
\newcommand{\grey}[1]{\textcolor[gray]{.66}{#1}}
\DeclareNewLayer[
background,
evenpage,
leftmargin,
contents={%
\vfil\hfil\rotatebox{90}{%
\fontsize{60}{100}\selectfont\grey\leftmark%
}\hfil\vfil
}]{markmargin-left}
\DeclareNewLayer[
background,
oddpage,
rightmargin,
contents={%
\vfil\hfil\rotatebox{-90}{%
\fontsize{60}{100}\selectfont\grey\rightmark%
}\hfil\vfil
}]{markmargin-right}
\DeclareNewPageStyleByLayers{markmargin}{markmargin-left,markmargin-right}
\pagestyle{markmargin}
%\automark[section]{section}
\manualmark
\renewcommand\section[1]{%
\clearpage%
\markboth{\textit{#1}}{\textit{#1}}
}
\parindent0pt
\begin{document}
\section{A.1 test page}
\blindtext
\begin{figure}[!ht]
\centering
\includegraphics[scale=.8]{example-image-a}
\end{figure}
\clearpage
\section{A.2 test page}
\blindtext
\begin{figure}[!ht]
\centering
\includegraphics[scale=.8]{example-image-a}
\end{figure}
\clearpage
\section{B.1 test page}
\blindtext
\begin{figure}[!ht]
\makebox[\paperwidth][c]{\includegraphics[scale=.8]{example-image-b}}
\end{figure}
\clearpage
\section{B.2 test page}
\blindtext
\begin{figure}[!ht]
\makebox[\paperwidth][c]{\includegraphics[scale=.8]{example-image-b}}
\end{figure}
\clearpage
\section{C.1 test page}
\blindtext
\begin{figure}[!ht]
\hspace{1.3cm}
\includegraphics[scale=.8]{example-image-c}
\end{figure}
\clearpage
\section{C.2 test page}
\blindtext
\begin{figure}[!ht]
% \hspace{-1.5cm}
\includegraphics[scale=.8]{example-image-c}
\end{figure}
\end{document}