For each JP2 image in a directory, generate derived image that discards user-defined number of quality layers. Requires Aware j2kdriver tool.

extractlayers.sh

#!/bin/bash
# Generate derived JP2s that discard user-specified number of quality layers from source JP2s
# Requires:
# - j2kdriver (Aware)
# 
# If you're using Windows you can run this shell script within a Cygwin terminal: http://www.cygwin.com/
#

# Installation directory
instDir="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

# **************
# USER I/O
# **************
# Check command line args
if [ "$#" -ne 3 ] ; then
    echo "Usage: extractlayers.sh sourceDirectory destinationDirectory layersdiscarded" >&2
    exit 1
fi

if ! [ -d "$1" ] ; then
    echo "directory must be a directory" >&2
    exit 1
fi

# Source directory
sourceDirectory="$1"

# Destination directory
destDirectory="$2"

# Layers to discard
layersdiscarded="$3"

# Aware ql argument
ql=$((layersdiscarded+1))

# Create destination directory if it doesn't  exist
if ! [ -d $destDirectory ] ; then
    mkdir $destDirectory
fi

# Normalise directories to absolute paths
sourceDirectory=$(readlink -f $sourceDirectory)
destDirectory=$(readlink -f $destDirectory)

# **************
# MAIN PROCESSING LOOP
# **************

# Select all files with extension .jp2.
# Now works for filenames that contain whitespace using code adapted from:
# http://stackoverflow.com/questions/7039130/bash-iterate-over-list-of-files-with-spaces/7039579#7039579
while IFS= read -d $'\0' file ; do
    fName="$file"

     # Base name (strip away path)
    fNameNoPath=$(basename "$fName")
    bName="${fNameNoPath%.*}"
    # Generate output file name
    outName="$destDirectory"$"/$bName"_lr.jp2
    
    # Run j2kdriver
    j2kdriver -i "$fName" -t  JP2 -ql $ql -o "$outName"

done < <(find $sourceDirectory -name '*.jp2' -type f -print0)