convert-double-pdfs-to-images

#!/bin/bash

# The user must supply a directory name to operate on
if [ "$1" == "" ]; then
  echo "Script requires a directory containing suitably named PDF files"
  exit 1
fi
cd $1

# Clean up the output files before starting
rm -f out-*.jpg fixed-*.jpg

# The files should be named using a scheme that ensures they appear in the right
# order. You should use A or B in the filename to indicate if it is the front or
# back side for the scan.
# Takes a set of scans 1A 1B 2A 2B 3A 3C and combines them together like so:
# 1. Take even PDF files and concatenate them
# 2. Take odd PDF files, and concatenate them in reverse order
# 3. Shuffle the pages together to convert double sided to single sided

EVEN=`ls -1 *[Aa].pdf | sort | tr '\n' ' '`
ODD=`ls -1 *[Bb].pdf | sort -r | tr '\n' ' '`

echo "Found even page PDFs = [$EVEN]"
echo "Found odd page PDFs  = [$ODD]"

pdftk $EVEN cat output /tmp/even.pdf
EVENPAGES=`pdfinfo /tmp/even.pdf | grep Pages: | awk -F':' '{ print $2 }' | tr -d ' '`
echo "Produced $EVENPAGES even pages"

pdftk $ODD cat output /tmp/odd.pdf
ODDPAGES=`pdfinfo /tmp/odd.pdf | grep Pages: | awk -F':' '{ print $2 }' | tr -d ' '`
echo "Produced $ODDPAGES odd pages"

pdftk A=/tmp/even.pdf B=/tmp/odd.pdf shuffle A Bend-1 output /tmp/shuffle.pdf
OUTPAGES=`pdfinfo /tmp/shuffle.pdf | grep Pages: | awk -F':' '{ print $2 }' | tr -d ' '`
echo "Produced $OUTPAGES shuffled output pages"

if [ $EVENPAGES != $ODDPAGES ]; then
  echo "Odd pages does not match even pages, scanner problem?"
  exit 1
fi
if [ $[EVENPAGES+ODDPAGES] != $OUTPAGES ]; then
  echo "Odd+Even pages does not match output pages, scanner problem?"
  exit 1
fi

# Split the single PDF into separate JPEG images named tmp-*.jpg
pdfimages -j /tmp/shuffle.pdf out

JPEGPAGES=`ls -1 out-*.jpg | wc -l`
echo "Produced $JPEGPAGES raw JPEG images"
if [ $JPEGPAGES != $OUTPAGES ]; then
  echo "Number of JPEG images does not match previous page count, file corruption problem?"
  exit 1
fi

for EVEN in `ls -1 out-[0-9][0-9][02468].jpg`; do
  echo "Rotating even file $EVEN 90 degrees to the right"
  jpegtran -rotate 90 -outfile fixed-$EVEN $EVEN
done

for ODD in `ls -1 out-[0-9][0-9][13579].jpg`; do
  echo "Rotating odd file $ODD 90 degrees to the left"
  jpegtran -rotate 270 -outfile fixed-$ODD $ODD
done

# Clean up the temporary files, leaving only the fixed up versions
rm -f out-*.jpg