#!/bin/sh -ex

# $1 file.pnm
# 600 dpi by default.

INPUT=$1
DPI=190
OUTPUT=`basename $INPUT .pgm`.djvu
TMPFILE=/tmp/tempfile

function threshold_mkbitmap
{
PPM=$1
PBM=$2
mkbitmap -s 1 -o "$PBM" "$PPM"
}

function threshold_netpbm
{
pamditherbw -threshold $1 | pamtopnm >$2

}

function threshold_netpbm2
{
pamthreshold -contrast 0.5 -dual=16x16  $1 |pamtopnm > $2

}

if [ $# -ne 1 ]; then
	echo "usage: $0 <file.pnm>"
	exit
fi

pnmnorm < "$INPUT" > "$TMPFILE.ppm"
threshold_netpbm2 "$TMPFILE.ppm" "$TMPFILE.pbm"

cjb2 -clean -dpi $DPI "$TMPFILE.pbm" "$TMPFILE.djvu"

djvumake "$OUTPUT" PPM="$TMPFILE.ppm" Sjbz="$TMPFILE.djvu"

rm -f "$TMPFILE.pbm"
rm -f "$TMPFILE.ppm"
rm -f "$TMPFILE.djvu"
echo Done: \"$OUTPUT\" created.