Script to run in a local directory to optimize all JPG and PNG images.

optimize_images.sh

#!/bin/bash

# This script relies on jpegtran, a tool included with libjpeg.
# libjpeg comes bundled with ImageMagick on most nix platforms:
#
#   Mac:
#   brew install imagemagick
#   brew install pngquant
#
#   Ubuntu/Debian:
#   sudo apt-get install gcc
#   sudo apt-get install imagemagick
#   sudo apt-get install libjpeg-progs
#   sudo apt-get install pngquant


function optimize_images() {

  # checks for the presence of jpegtran, which we use for image optimization
  command -v jpegtran >/dev/null 2>&1 || { echo >&2 "I require jpegtran but it's not installed. Aborting."; exit 1; }

  # checks to make sure the desired working directory exists
  read -p "Local Files Root Directory (./files): " DIR
  if [ ! -d $DIR ]; then
    echo "$DIR is not a directory. Aborting"
    exit 1
  fi

  # remember where we started off so we can return later
  # cd into working directory
  echo "Changing to $DIR"
  CUR_DIR=$(pwd)
  cd $DIR

  # optimize jpgs
  FILES=$(find . -iname '*.jpg' -o -iname '*.jpeg')
  for F in $FILES; do
    echo "Optimizing: $F"
    jpegtran -copy none -progressive -outfile $F $F
  done

  # optimize pngs
  FILES=$(find . -iname '*.png')
  for F in $FILES; do
    echo "Optimizing: $F"
    pngquant --force --ext=.png --speed=8 --quality=65-85 $F
  done

  echo "Done"

  # return back to where we came from
  cd $CUR_DIR
}

optimize_images