extruding sprite tiles

convert source_file.png -crop 16x +repage png32:slice_file_%02d.png
for f in slice_file_*.png; do
    convert $f \( +clone -gravity West -crop 1x+0+0 +repage \) \
    +swap \( +clone -gravity East -crop 1x+0+0 +repage \) \
    +append png32:pad_file_${f//[!0-9]}.png
done
convert pad_file-*.png +append png32:semipadded_file.png
convert semipadded_file.png -crop x16 +repage png32:padded_slice_file_%02d.png
for f in padded_slice_file_*.png; do
    convert $f \( +clone -gravity North -crop x1+0+0 +repage \) \
    +swap \( +clone -gravity South -crop x1+0+0 +repage \) \
    -append png32:full_padded_file_${f//[!0-9]}.png
done
convert full_padded_file_*.png -append png32:output_file.png