Prototype png color reduction script/linter

check-image.sh

#! /bin/sh

QUALITY=95
DEPTHS="256 128 64 32 8 4 2"

totalSaved=0

for name in `find "$1" -name "*.png" -not -name "*-fs8.png"`; do
  output=

  newName=${name%.png}-fs8.png
  originalSize=`stat -f %z "$name"`
  colors=`identify -verbose "$name" | grep Colors: | awk '{ print $2 }'`

  for depth in $DEPTHS; do
    if [ "$colors" != "" ]; then
      if [ "$depth" -ge "$colors" ]; then
        continue;
      fi
    fi

    log=`pngquant -fv --speed 1 --quality $QUALITY-100 $depth -- "$name" 2>&1`

    if [ $? -eq 0 ]; then
      pngout $newName > /dev/null
      newSize=`stat -f %z "$newName"`
      deltaCheck=$(( originalSize - newSize ))

      if [ $deltaCheck -gt 0 ]; then
        #echo "$log"
        mse=`echo "$log" | grep MSE | sed 's/.*\(MSE=.*\)/\1/'`
        bytes=$deltaCheck
        percent=$(( 100-(100*$newSize / $originalSize) ))
        output="$output\n\t-$bytes bytes Colors: $depth $mse Size: $newSize $percent% smaller"
        #compare -verbose -metric rmse $name $newName $name-compare-fs8.png
      else
        rm $newName
      fi
    fi
  done

  if [ "$output" != "" ]; then
    totalSaved=$(( totalSaved + bytes ))
    echo "$name size: $originalSize colors: $colors $output"
  fi
done

echo "Possible savings: $totalSaved bytes"