Ubuntu – How do you create a PDF from multiple images? Now with more grid problems

pdfprinting

So I have a ton of 825×1125 images ( (>300, in png format but I can make jpegs). I need to create a printable PDF with them (to print playing card prototypes). They have to be in a 3×3 grid pattern in the Letter format (they're meant for 300dpi).

I'm pretty sure I can batch resize them beforehand if it helps.

I'm guessing you can do this with convert or something but for the life of me I can't figure it out.

Thanks

• If you know a bit of LaTeX, I would use pdflatex for this --- it's quite easy to script.

The trick is generating a file with this header:

\documentclass[letterpaper]{report}
\usepackage{graphicx}
\begin{document}


and then for each line of photos

\includegraphics[width=0.3\textwidth]{file01-01.png}\quad
\includegraphics[width=0.3\textwidth]{file01-03.png}\par


--- these are three images on a line, separated by a bit of space; and after three lines you put a

\clearpage


and at the end of the file a

\end{document}


You can generate the file with the language you want; save it in a file called whatever.tex and then process it with

 pdflatex whatever


With more LaTeX you can easily add captions, titles, frames or whatever you want. I understand it's a bit of steep curve to learn, but it's quite useful.