stitch.sh

#! /bin/bash -e
# https://wiki.panotools.org/Panorama_scripting_in_a_nutshell
# http://hugin.sourceforge.net/tutorials/scans/en.shtml

# This is a tool to vertically stitch together screenshots of black and white
# scans.
#
# Install:
#
#   brew cask install hugin
#

# Usage:
#
#   ./stitch.sh *.png

BIN="/Applications/Hugin/tools_mac"
TMP="$(mktemp -d)"
PROJECT=p.pto
PREFIX=stitch

(
IFS=
for img in $* ; do
  cp "$img" "$TMP/"
done
)

pushd "$TMP"

echo "=> creating project"
echo $@
"$BIN/pto_gen" -o "$PROJECT" --projection=0 --fov=10 *.png

echo "=> generating control points"
"$BIN/cpfind" --multirow -o "$PROJECT" "$PROJECT"

echo "=> cleaning"
"$BIN/cpclean" -o "$PROJECT" "$PROJECT"

echo "=> optimizing"
"$BIN/linefind" -o "$PROJECT" "$PROJECT"
"$BIN/autooptimiser" -a -l -s -m -o "$PROJECT" "$PROJECT"
"$BIN/autooptimiser" -m -o "$PROJECT" "$PROJECT"

echo "=> setting up the output"
# https://manpages.debian.org/testing/hugin-tools/pano_modify.1.en.html
"$BIN/pano_modify" -o "$PROJECT" --projection=0 --fov=AUTO --center \
  --canvas=AUTO "$PROJECT"

echo "=> stitching"
"$BIN/hugin_executor" --stitching "--prefix=$PREFIX" "$PROJECT"
echo "=> trimming"
# remove '-colorspace gray' to preserve color
convert "$PREFIX".tif -trim -colorspace gray "$PREFIX".png
if [ x"$(which optipng)" != x ]; then
  echo "=> optimizing the output"
  optipng -o1 "$PREFIX".png
fi

popd
mv "$TMP/$PREFIX.png" ./
rm -rf "$TMP"

echo "Done: $PREFIX.png"