Exctract faces and make collage out of them

extract-face-make-collage.sh

i=0
for file in *.jpg; do
  echo "$i $file"
  name=$(basename "$file")
  facedetect "$file" | while read x y w h; do
    convert "$file" -crop ${w}x${h}+${x}+${y} -resize 640x640 "face_${i}.${name##*.}"
    i=$((i+1))
  done
  i=$((i+1))
done

ls face_* -l | wc -l
montage -geometry +0+0 -tile 5x5 face*.jpg result.jpg