Find png files that don't have transparency and convert to jpg, also recompress all jpg files for the web

optimize_images.sh

#!/bin/sh

echo You should have the project tracked by version control in case something goes wrong.
printf 'Press any key to continue...'

read -r
path=${1:-.}
echo Optimizing images in "$path"

if [ -z "$(command -v jpeg-recompress)" ] || [ -z "$(command -v ladon)" ] || [ -z "$(command -v mogrify)" ]; then
  echo You need ladon, ImageMagick, and jpeg-archive to be able to run this script
  exit 1
fi

transparency_test() {
  if [ "$(identify -format '%[channels]' "$1")" = "srgb" ]; then
    echo "$1"
  fi
}

export -f transparency_test
find_pngs_with_no_tranparency() {
  find "$path" -type f -name "*.png" -exec sh -c 'transparency_test "$1"' _ {} \;
}

pngs=$(find_pngs_with_no_tranparency)

if [ "$pngs" ]; then
  echo "$pngs" | xargs mogrify -format jpg
  echo "$pngs" | xargs rm

  ladon "$path/**/*.jpg" -- jpeg-recompress FULLPATH FULLPATH

  echo "Done!"
else
  echo "No PNG files to compress!"
fi