View source for Cutting up pages in a scanned PDF

If you have a PDF which has been scanned on a photocopier as double-page-spreads from a book, it can be convenient for on-screen reading to have the left and right pages separated.

To convert such a PDF:

<source lang=sh>
# this will generate files for each page of the document, so work in a new subdirectory:
mkdir temp
cd temp
# split out the images from the file
pdfimages ../scanned-document.pdf page
# rotate the pages as needed, cut in half, rename to preserve ordering
for I in `ls page-*.ppm`; do convert -rotate 270 $I -crop 50%x100% +repage rot-$I-%d.ppm; done;

# here, take a quick look at the rot* files are remove any that are unwanted

# recompose into a new PDF document
convert rot*.ppm chopped-document.pdf
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