resizer.sh

#!/bin/bash -e
# Make sure you have installed ImageMagick
# http://cactuslab.com/imagemagick/

# Ensure we're running in location of script.
cd "`dirname $0`"

for f in *; do
  if [[ $f == *@3x* ]];
    then
    echo "$f -> ${f//@3x/@2x}, ${f//@3x/}"
    convert "$f" -resize 66.66666% "${f//@3x/@2x}"
    convert "$f" -resize 33.33333% "${f//@3x/}"
  fi
done

echo "Complete"

Thanks for sharing David,

No files converted, when I run it just says 'Complete' - so I added echo $f at between line 8 and 9 and it logs the filenames in /usr/local/bin instead of my current working directory - what did I miss?

Steps for me...

• Installed Image Magick http://cactuslab.com/imagemagick/ (I chose the first option so Quartz wasn't required)
• Download the resizer.sh script
• Moved resizer.sh from downloads to '/usr/local/bin'
• Opened terminal
• cd - Moved to the folder with my image(s) with @3 in the filename (pwd confirms I'm in the right folder)
• typed 'resizer.sh' (also tried 'resizer.sh /Users/Rob/Desktop/test')

@SpikyOrange You missed:

# Ensure we're running in location of script.
cd "`dirname $0`"

Move the the script to the folder where your images are and run it.