[Tex/LaTex] Always scale and clip background image so it fills the page

backgroundscropgraphicsscaling

I have learned from other answers how to use an image file as background and make it transparent. Since my background files do not necessarily have the exact page dimensions (they are provided by users), I want to scale and clip them to fit.

I have found, however, that using

\includegraphics[width=\paperwidth,height=\paperheight,keepaspectratio,clip]{#1}

does not always scale correctly; landscape-oriented images are scaled so widths fit and then not clipped at all if they are very flat, so a white bar remains. For example, this is using a 1600×750 image on a US Letter landscape page:

\documentclass[landscape]{article}
\usepackage{eso-pic,graphicx}
\pagestyle{empty}
\begin{document}
  \AddToShipoutPicture*{%
    \put(0,0){%
      \parbox[b][\paperheight]{\paperwidth}{%
        \includegraphics[width=\paperwidth,height=\paperheight,keepaspectratio,clip]{test.png}%
      }%
    }%
  }%
  \phantom{lorem ipsum}
\end{document}

enter image description here

How can I tell includegraphics to always scale the shorter dimension to fit?

Best Answer

As far as I can tell, you can't. adjustbox, always worth a look, does not seem to offer the necessary option(s), either.

Luckily, we can hack it. Observe that

\includegraphics[width=\paperwidth,keepaspectratio,clip]{img}

works well for portrait images -- scaling them so the width fits and clip -- and the opposite

\includegraphics[height=\paperheight,keepaspectratio,clip]{img}%

works for landscape images. So we can choose the correct version according to image dimensions which version to use:

\settoheight\imageheight{\includegraphics{img}}%
\settowidth\imagewidth{\includegraphics{img}}%
\ifthenelse{\dimtest{\imageheight}{>=}{\imagewidth}}{%
  \includegraphics[width=\paperwidth,keepaspectratio,clip]{img}%
}{%
  \includegraphics[height=\paperheight,keepaspectratio,clip]{img}%
}%

Note that this requires package xifthen. The example then ends up compiling to:

enter image description here

I have not figured out yet how to choose a well-defined part of the image, say the middle part, when clipping; it seems to work from the left resp. the bottom by default. Also, the clipped image seems to produce Overful \hbox warnings.

Related Solutions

[Tex/LaTex] Scale image to page width

Use \textwidth for the width of the text block, and \paperwidth if you want to fit it into the paper width. You could also use \linewidth if you want to fit the image within the line width, which may vary depending on the environment you're in (for example, within a list like enumerate).

Note that if you use \includegraphics outside a figure or table environment, you might want to prepend it with \noindent to avoid the image being pushed over to the right by \parindent. Also, centering the image within the page width (when using \paperwidth) is best obtained using

\begin{center}
  \makebox[\textwidth]{\includegraphics[width=\paperwidth]{...}}
\end{center}

\noindent\makebox[\textwidth]{\includegraphics[width=\paperwidth]{...}}

In both instances it typesets a box of width \textwidth, while the contents may stretch outside this width (given by width=\paperwidth). Fixing it to \textwidth avoids Overfull \hbox warnings.

This works as expected within the article and report document class, while some horizontal re-adjustment is required in book. For completeness, and without resorting to page numbering issues that may occur at shipout if the image is placed near a page break, the following \centerimg[<options>]{<image>} command works for all standard document classes, including book:

\documentclass{article}
\usepackage{graphicx,changepage}

\newcommand{\adjustimg}{% Horizontal adjustment of image
  \checkoddpage%
  \ifoddpage\hspace*{\dimexpr\evensidemargin-\oddsidemargin}\else\hspace*{-\dimexpr\evensidemargin-\oddsidemargin}\fi%
}
\newcommand{\centerimg}[2][width=\textwidth]{% Center an image
  \makebox[\textwidth]{\adjustimg\includegraphics[#1]{#2}}%
}

\begin{document}
\mbox{} \par
\noindent\centerimg[width=\paperwidth,height=200pt]{tiger}

\newpage

\mbox{} \par
\noindent\centerimg[width=\paperwidth,height=200pt]{tiger}
\end{document}

The horizontal adjustment for book (obtained via \adjustimg) depends on whether the page number is odd or even. The above MWE, with the tiger image, compiles to the output:

enter image description here

[Tex/LaTex] Background clip to text Tikz

Solution without TikZ

Using text as clip path is supported by package pdfrender if pdfTeX (or LuaTeX) is running in PDF mode.

\pdfsave and \pdfrestore saves and restores the current graphics state, thus that the clipping ends after \pdfrestore. Since the graphics state include the current transfer matrix (e.g., the current point on the PDF page), the command pair must be used on the same TeX location. Otherwise the TeX coordinate system and the PDF coordinate system would go out of sync.

Full example:

\documentclass{article}
\usepackage{graphicx}
\usepackage{pdfrender}
\usepackage{tgheros}
\usepackage{varwidth}

\newcommand*{\TextImage}[2]{%
  \sbox0{%
    \sffamily
    \bfseries
    \begin{varwidth}{\linewidth}%
      \uppercase{\ignorespaces#1\ifhmode\unskip\fi}%
    \end{varwidth}%
  }%
  \mbox{%
    \pdfsave
    % Set clip path
    \pdfrender{TextRenderingMode=Clip}%
    \rlap{%
      \copy0 %
    }%
    % Now the image or whatever is provided in #2 is used.
    \rlap{%
      \def\width{\wd0 }%
      \def\depth{\dp0 }%
      \def\height{\ht0 }%
      \def\totalheight{\dimexpr\ht0+\dp0\relax}%
      \raisebox{-\dp0}{#2}%
    }%
    \pdfrestore
    % Inform TeX about the text dimensions
    \phantom{\copy0}%
  }%
}

\begin{document}
  \TextImage{%
    This text clips the\\
    background image%
  }{%
    \includegraphics[
      width=\width,
      height=\totalheight,
      viewport=0 0 {10mm} {5mm},
    ]{bg.pdf}%
  }
\end{document}

The background image bg.pdf was generated with:

\documentclass[tikz]{standalone}
\begin{document}
  \begin{tikzpicture}
    \pgfmathsetseed{10000}
    \foreach \i in {1, ..., 500} {
      \pgfmathsetmacro\colred{rnd}
      \pgfmathsetmacro\colgreen{rnd}
      \pgfmathsetmacro\colblue{rnd}
      \definecolor{col}{rgb}{\colred,\colgreen,\colblue}
      \pgfmathsetlengthmacro\rad{.1mm + 10mm*rnd/sqrt(\i)}
      \fill[col] (rnd, rnd) circle[radius=\rad];
    }
    \pgfresetboundingbox
    \useasboundingbox (0, 0) (1, 1);
  \end{tikzpicture}
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Scale image to page width

[Tex/LaTex] Background clip to text Tikz

Solution without TikZ

Related Question