Start with a wide long image. This is just a screen shot of my desktop. widescreen.png

Convert it to postscript using convert from ImageMagick

# install ImageMagick
sudo dnf install ImageMagick

convert widescreen.png widescreen.ps

Use poster to chop and format the long wide image into a print friendly multi-page postscript document

This command says make the cut margins four percent of the page size (-c4%) use cut marks -C1. Make it 1 x 3 A4 pages tall (-p 1x3A4) output it to a file with -o widescreen-4pct.ps and use widescreen.ps as the input

poster -c4% -C1 -p 1x3A4 -o widescreen-4pct.ps widescreen.ps

By default poster creates 6 pixel overlap so you can cut it and overlap the pages without there being a gap

Finally convert it to PDF

ps2pdf widescreen-4pct.ps widescreen-4pct.pdf

The PDF looks like this in the default Gnome viewer.