compress_images.sh

# Example usage: sh compress_images.sh -i=images -o=compressed_images -w=1280 -e=jpg -f=webp

# Set default values
width="1280"
src="./images"
dest="./compressed_images"
extension="jpg"
output_format="webp"

function print_help {
  echo "Usage: sh compress_images.sh -i=images -o=compressed_images -r=1280 -e=jpg -f=webp"
  echo "Options:"
  echo "-i, --input=       Source directory (default: images)"
  echo "-o, --output=      Destination directory (default: compressed_images)"
  echo "-r, --resolution=  Resolution (default: 1280)"
  echo "-e, --extension=   Extension (default: jpg)"
  echo "-f, --format=      Output format (default: webp)"
  echo "-h, --help         Display help"
}

# Take inupt from user
for i in "$@"; do
  case $i in
  -i=* | --input=*)
    src="${i#*=}"
    shift
    ;;
  -o=* | --output=*)
    dest="${i#*=}"
    shift
    ;;
  -w=* | --width=*)
    width="${i#*=}"
    shift
    ;;
  -e=* | --extension=*)
    extension="${i#*=}"
    shift
    ;;
  -f=* | --format=*)
    output_format="${i#*=}"
    shift
    ;;
  -h | --help)
    print_help # Display help
    exit 0
    ;;
  *)
    print_help # Display help
    exit 1
    ;;
  esac
done

# Throw error if source directory doesn't exist
if [ ! -d "$src" ]; then
  echo "Source directory doesn't exist"
  exit 1
fi

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

if [ "$output_format" == "webp" ]; then
  mogrify -format webp -quality 82 -path $dest/ $dest/*.$extension
  exit 0
fi

if [ "$output_format" == "jpg" ]; then
  # This is taken from https://www.smashingmagazine.com/2015/06/efficient-image-resizing-with-imagemagick/
  mogrify -path $dest/ -filter Triangle -define filter:support=2 -thumbnail $width -unsharp 0.25x0.08+8.3+0.045 -dither None -posterize 136 -quality 82 -define jpeg:fancy-upsampling=off -define png:compression-filter=5 -define png:compression-level=9 -define png:compression-strategy=1 -define png:exclude-chunk=all -interlace none -colorspace sRGB $src/*.$extension
  exit 0
fi

echo "Invalid output format"
exit 1