Iterate over an array of image sizes, and move them to a new folder
#!/bin/bash
targetDir="$HOME/Pictures/iPhoto-bibliotek.photolibrary"

echo -e "Scanning \033[0;32m$targetDir\033[0m"
find $targetDir -type f \( -iname \*.jpg -o -iname \*.png -iname \*.bmp -iname \*.jpeg \) 2&gt;/dev/null | \
    while read -r filename; do
        hw="$(sips -g pixelHeight -g pixelWidth "$filename" 2&gt;/dev/null)"
        h="$(awk '/pixelHeight/{print $2}'&lt;&lt;&lt;"$hw")"
        w="$(awk '/pixelWidth/{print $2}'&lt;&lt;&lt;"$hw")"

        case ${h}x${w} in
            450x600) echo mv "$filename" $(pwd)/120x120images
                     ;;
            120x120) echo mv "$filename" $(pwd)/120x120images
                     ;;
            269x360) echo mv "$filename" $(pwd)/120x120images
                     ;;
            *)       echo "$filename ignored"
                     ;;
        esac
done


You can add additional dimensions in the same way, or change the target directory if required. Also, remove the echo once it works.