split.sh

image=in.png
convert ${image} -resize "32x32!" -modulate 100,300,100 "single.png"

for ((z=2; z<= 8; z+=1))
do
height=$((z * 32))
convert ${image} -resize "${height}x${height}!" -modulate 100,300,100 "temp${z}.png"
if [ -d "${z}" ]
then
    rm -dr $z
fi
mkdir $z
echo "spliting sprite sheet at zoom level ${z}"
xi=0
    for ((x=0; x<height; x+=32))
    do
    xi=$((xi+1))
    yi=0
        for ((y=0; y<height; y+=32))
        do
        yi=$((yi+1))
            convert "temp${z}.png" -crop "32x32+${x}+${y}" "$z/s${yi}-${xi}.png"
        done
    done
    rm "temp${z}.png"
done