Convert left+right pictures from a stereo MPO into a left-right diptych picture

mpo2diptych.sh

#!/usr/bin/env bash
#
# ***** Warning: this is not production-quality! *****
#
# this will extract the left + right images from all passed
# .MPO files, crop them to a percentage of the width (75% by
# default), and stitch them together into a diptych.
#
# Based on https://photo.stackexchange.com/a/100402/57928

percent=75

# if the first argument is a number, use it for crop percentage
if [[ $1 =~ ^[0-9]+$ ]] ; then
	percent=$1
	shift 1
fi

for i in "$@" ; do
    j="${i#*/}"
    k="${j%.[mM][pP][oO]}"
    width=$(identify -format "%w" "$i")
    # offset from the left to the beginning of the 75% image
    offset=$((width*(100-percent)/200))

    # extract left images
    exiftool -trailer:all= "$i" -o "${k}.left.jpg"
    exiftool -TagsFromFile "$i" "${k}.left.jpg"

    # extract right images
    if exiftool "$i" | grep "MP Image 3" ; then
        # Samsung NX 45mm f/1.8 2D/3D
        exiftool "$i" -mpimage3 -b > "${k}.right.jpg"
        exiftool -TagsFromFile "$i" "${k}.right.jpg"
    else
        # Fujifilm Real 3D W3
        exiftool "$i" -mpimage2 -b > "${k}.right.jpg"
        exiftool -TagsFromFile "$i" "${k}.right.jpg"
    fi

    # crop the left + right images to allow for easier vertical viewing
    convert "$k.right.jpg" -crop $percent%x100%+$offset+0 +repage "$k.right.crop.jpg"
    convert "$k.left.jpg" -crop $percent%x100%+$offset+0 +repage "$k.left.crop.jpg"

    # combine l+r into one diptych
    montage "$k.left.crop.jpg" "$k.right.crop.jpg" -tile 2x1 -geometry +0+0 "$k.stereo.jpg"

    # remove the intermediates
    rm -f "$k".{left,right}{,.crop}.jpg "$k".{left,right}.jpg_original
done