A simple script for processing a directory of PNG images converted to JPG and compressed to Lepton and renamed into a sequence while retaining the modification dates.

archive-lepton.sh

#!/bin/bash

# This simple script processes screenshots taken with a PS3 and does multiple things:
# - Changes all PNG files to JPG using imagemagick
# - Compresses all files into Lepton-format images
# - Reapplies the original modification date for metadata retention.

# Prepare a file list, sorted by modification date.
rm FILELIST 2>/dev/null
ls -tdr1 *.png > FILELIST; 

# Initialize necessary variables.
LIST=`cat FILELIST`

SEQ=1
if [ $# -eq 1 ]; then SEQ="$1"; fi

while read file;
do
   # Track the current modified date
   MDATE=`stat -c '%y' "$file"`


   # Then apply the desired operations and apply the modified date onto the new file.
   # If everything works without errors, remove the old file.
   mv "$file" "${SEQ}.png"
   mogrify -format jpg "${SEQ}.png"
   rm "${SEQ}.png"
   lepton "${SEQ}.jpg" "${SEQ}.jpg.lep"
   touch -d "${MDATE}" "${SEQ}.jpg.lep"
   rm "${SEQ}.jpg"   

   # Proceed to the next file and count up on the sequence.
   SEQ=$(( $SEQ + 1 ))
done <FILELIST

# Clean up the temporary file list.
rm FILELIST 2>/dev/null