Pandoc disable figure stretching from Markdown to PDF conversion - pdf

Question

I create PDF documents from Markdown documents using the simplest pandoc command:
pandoc my.md -o my.pdf
The figures inside the PDF are all stretched, i.e: 100% width.
Which configuration should I give to pandoc to leave the figures as is without changing figure size.

Answer 1

Currently you cannot control that feature directly from Markdown.
In recent months there have been some discussions going on in the Pandoc developer + user community about how to best implement it and create an easy-to-use syntax, for example
![Image Caption](./path/to/image.jpg "Image Comment"){width="60%", height="150px"}
(Warning: Example only, made up on the fly and drawn out of thin air by myself -- can't remember the latest state of the discussion...) This is designed to then transfer to all the supported output formats which can contain images, not just PDF.
So this is planned to be a major new feature for the next major release of Pandoc.
As you may or may not know, Pandoc doesn't create the PDFs itself. It produces LaTeX and employs LaTeX technology (by default its pdflatex command) to convert the LaTeX to PDF (then deleting the intermediate LaTeX files).
To execute some (limited) control about how the LaTeX/PDF pages (or other outputs) look like, Pandoc uses template files. You can look at the exact template definitions your own Pandoc version uses for LaTeX/PDF output by running
pandoc -D latex
So if you are a LaTeX hacker (or know one), you are able to modify that or create your own template from scratch.
In the current release of Pandoc (v1.13.2.1), there is this code snippet in the LaTeX template:
\makeatletter
\def\maxwidth{\ifdim\Gin#nat#width>\linewidth\linewidth\else\Gin#nat#width\fi}
\def\maxheight{\ifdim\Gin#nat#height>\textheight\textheight\else\Gin#nat#height\fi}
\makeatother
% Scale images if necessary, so that they will not overflow the page
% margins by default, and it is still possible to overwrite the defaults
% using explicit options in \includegraphics[width, height, ...]{}
\setkeys{Gin}{width=\maxwidth,height=\maxheight,keepaspectratio}
This should keep the original image sizes if they fit into the page width, and scale them down to the page width if they don't.
If this is not the behavior you experience with your PDF output, I suspect you are an a rather old version of Pandoc.
For using your own template instead of the builtin internal one, you can add
--template=/path/to/myown-template.latex
to the Pandoc command line.

Answer 2

#KurtPfeifle Thanks for your help. I updated the latex to set static width and hight for the images using the tip.
In my latex template I have:
\setkeys{Gin}{width=128pt,height=192pt,keepaspectratio}
This works great for the mobile images. But I also have a cover page, where the cover figure is now small sized.
I tried creating 2 different latex files and combining them but the figure sizes are back to being stretched:
pandoc _cover_page.md -o _cover_page.tex
pandoc ... -template=mobile_images.latex -o remaining.tex
pandoc _cover_page.tex remaining.tex -o out.pdf
Is there an easy way to combine latex files whicih obey the templates in Pandoc?
I can create 2 pdf files: cover.pdf and remaining.pdf, and combine them too. Is there an easy tool that you know?