[Tex/LaTex] How to center the logo on the page

eso-picgraphics

What I want

The logo (example-image-a) should be centered on the page.

What I don't understand

Can somebody explain me what the coordinates in \put(100,100) mean? Are this mm, em or px? I don't get it.

MWE

\documentclass{scrbook}

\usepackage{mwe} % example images

\usepackage{eso-pic}

\begin{document}

\chapter{bla}

\AddToShipoutPicture*
{%
\put(100,100) % the specific point of the page with coordinates (x=100, y=100)
 {\includegraphics[scale=0.5]{example-image-a}}%
}

\end{document}

Best Answer

The coordinates are multiples of \unitlength. However, for centering it's easier to use picture, that allows explicit lengths.

\documentclass{scrbook}

\usepackage{graphicx}
\usepackage{eso-pic}
\usepackage{picture} % explicit units in picture commands

\begin{document}

\chapter{bla}

\AddToShipoutPicture*{%
  \put(.5\paperwidth,.5\paperheight)% center of the page 
    {\makebox(0,0){\includegraphics[scale=0.5]{example-image-a}}}%
}

\end{document}

With \makebox(0,0) the object is placed in a zero width and height box, with the reference point at the center of the object, so you don't even need to measure it.

enter image description here

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