Embedding images explodes generated PDF size

Question

I am using

$ pdflatex --version
pdfTeX 3.14159265-2.6-1.40.18 (TeX Live 2017/Debian)
kpathsea version 6.2.3

to compile a 30-page pdf output. Twelve of the pages look like this (the rest are only text):

All items are generated by this code:

\newcommand{\weapon}[8]
{
\begin{multicols}{2}
  \noindent \textbf{#2} \\
  Необходима сила: #3  \\
  Обсег: #4  \\
  Щети: #5  \\
  Свойства: #6  \\
  Маса: #7  \\
  Стойност: #8  \\
  \includegraphics[height=0.13\textheight]{../images/#1}~
\end{multicols}
\vspace{0.01cm}
}

This bring the file size to:

remote: warning: File build/elementaris-fantasy.pdf is 63.06 MB; this is larger than GitHub's recommended maximum file size of 50.00 MB

The images I am using are not scaled and some of them are quire large.

How can I reduce the size of the PDF file? The purpose of the PDF is to be printed on sheets of paper as reference for a game.

Answer 1

You can use \DeclareGraphicsRule to call a resize command (externally) on files with the specified extension. The pdf will be smaller because it uses the resized image file.

In the MWE below the size is hardcoded to a height of 100px. The rule can be declared and subsequently replaced by a dummy rule at any point in the document, to avoid resizing jpg files in other parts of the document. Note however that the conversion is cached per file, so you cannot include a resized image and later include the full-size image from the same file.

The example image is taken from Wikipedia (https://commons.wikimedia.org/wiki/File:Bodiam-castle-10My8-1197.jpg).

Code (compile with --shell-escape):

\documentclass{article}
\usepackage{graphicx}
\begin{document}
% remove these two lines to reduce the pdf filesize
Before \texttt{\textbackslash DeclareGraphicsRule}:\\
\includegraphics[scale=0.2]{Bodiam-castle-10My8-1197.jpg}

% resize rule
\DeclareGraphicsRule{.jpg}{jpg}{.jpg}{`convert -geometry x100 #1 `basename #1 .jpg`-jpg-converted-to.jpg}

After \texttt{\textbackslash DeclareGraphicsRule}:\\
\includegraphics[scale=1.0]{Bodiam-castle-10My8-1197.jpg}
% dummy rule
\DeclareGraphicsRule{.jpg}{jpg}{.jpg}{`convert #1 `basename #1 .jpg`-jpg-converted-to.jpg}
\end{document}

Result:

Answer 2

You can compress the pdf using ghostscript. The relevant command line option is -dPDFSETTINGS= (see this question for details).

I use the following script for the compression (to medium resolution):

#!/bin/bash
INPUT="$1"
if [[ ! -f "$INPUT" ]]; then
   echo "File not exist \"$INPUT\""
   exit 1
fi
OUTPUT="$2"
if [[ -f "$2" ]]; then
    echo "File exists \"$2\""
    exit 1
fi
OUTPUT=${OUTPUT:-${INPUT%.*}.pdf}
[[ $# > 2 ]] && (echo "Extra arguments found: \"$*\""; exit 1)
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile="$OUTPUT" "$INPUT"