Wrapper for unpaper. Input is a double sided pdf book (scanned)

unpaper_pdf.sh

#!/bin/bash

# Usage: ./script.sh file.pdf
# Generate .png for each page on the PDF, assuming that the PDF is a scanned book.
# unpaper will crop and correct inclination and delete artifacts of each page

# Requirements:
# Ghostscript
# Unpaper (on arch repositories and https://github.com/Flameeyes/unpaper)
# basename (Maybe on coreutils package)1
# pnm2png/png2pnm (Maybe on libpng package)

if [ "$#" -lt 1 ]; then
    echo "unpaper_pdf - Generates a .png page for each input page of PDF"
    echo "Usage: unpaper_pdf.sh <pdf_file>"
    exit 1;
fi

OUTNAME=$(basename $1 .pdf)

# Convert PDF to PNG with Postscript
gs -sDEVICE=pngalpha -o %02d.png -r400 $1


# Assuming that in the current folder all the png files will be the 
# sheets of the scanned book (in PDF)
for FOLIO_PNG in $(ls *.png | cat)
do
	FOLIO_BASE=$(basename $FOLIO_PNG .png)
	FOLIO_PNM="${FOLIO_BASE}.pnm"
	png2pnm -r $FOLIO_PNG $FOLIO_PNM
	rm $FOLIO_PNG
	unpaper --layout single $FOLIO_PNM $OUTNAME-$FOLIO_BASE-%02d.pnm
	rm $FOLIO_PNM
	
	ls $OUTNAME-$FOLIO_BASE-*.pnm
	
	# Convertimos todos los PNM generados a PNG (son mas pequeños)
	for PAGE_PNM in $(ls $OUTNAME-$FOLIO_BASE-*.pnm | cat)
	do
		PAGE_BASE=$(basename $PAGE_PNM .pnm)
		PAGE_PNG="${PAGE_BASE}.png"
		pnm2png $PAGE_PNM $PAGE_PNG
		rm $PAGE_PNM
	done
done