Compresses and optimizes png image sizes for a given file or directory via pngquant.

optimizeImage.sh

#!/bin/bash
# Compresses and optimizes png image sizes for a given file or directory.
# @author: Jonathan Cardasis

CHECK_MARK="\033[0;32m\xE2\x9C\x94\033[0m"
PNGQUANT_BINARY_URL="https://pngquant.org/pngquant.tar.bz2"

optimize() {
  ORIGINAL_PATH="$1"
  NEW_PATH="$ORIGINAL_PATH.new"
  pngquant --skip-if-larger "$ORIGINAL_PATH" --output "$NEW_PATH"
  if [ "$?" -eq 0 ]; then
    rm "$ORIGINAL_PATH"
    mv "$NEW_PATH" "$ORIGINAL_PATH"
  fi
}

kb_count_of() {
  echo $(bc <<< "scale=2; $(wc -c "$1" | awk '{print $1}')/1000")
}

if [ "$#" -lt 1 ]; then
  echo "Provide a file or directory to optimize."
  exit 1
fi

# Check for pngquant installation
if [ "$1" == "--install" ]; then
  TEMP_DIR=`mktemp -d -t 'pngquant'`
  cd "$TEMP_DIR"

  curl -sS "$PNGQUANT_BINARY_URL" | tar xf - && \
  cp pngquant /usr/local/bin
  exit_code=$?

  if [ $exit_code -eq 0 ]; then
    echo "pngquant installed successfully."
  else
    echo "pngquant failed to install."
  fi

  rm -r "$TEMP_DIR"
  exit $exit_code
elif ! command -v pngquant > /dev/null; then 
  echo "pngquant is not installed. Run with the '--install' flag to install pngquant."; 
  exit 1
fi

# Optimize
echo -e "\n\033[4mOptimizing Images\033[0m"
total_original_kb=0
optimized_total_kb=0

if [ -f "$1" ]; then
  total_original_kb=$(kb_count_of "$1")
  optimize "$1"
  optimized_total_kb=$(kb_count_of "$1")
elif [ -d "$1" ]; then
  FILES=()
  while IFS=  read -r -d $'\0'; do
    FILES+=("$REPLY")
  done < <(find "${1%/}" -name "*.png" -print0)

  total_files="${#FILES[@]}"
  echo "count: $total_files"

  for filepath in "${FILES[@]}"; do
    filename=$(basename "$filepath")
    echo -n "Optimizing $filename ..."

    original_size_kb=$(kb_count_of "$filepath")
    total_original_kb=$(bc <<< "$total_original_kb + $original_size_kb")

    optimize "$filepath" > /dev/null 2>&1
    
    optimized_size_kb=$(kb_count_of "$filepath")
    optimized_total_kb=$(bc <<< "$optimized_total_kb + $optimized_size_kb")
    percent_diff=$(bc <<< "scale=2; ($original_size_kb-$optimized_size_kb)/$original_size_kb * 100")

    echo -e "\r${CHECK_MARK} Optimized $filename | \033[0;32m${percent_diff}% smaller\033[0m"
  done
  echo ""
fi

savings_size_kb=$(bc <<< "$total_original_kb-$optimized_total_kb")
echo -e "Finished optimizing. \033[0;32m${savings_size_kb}Kb saved.\033[0m"