use imagemagick to crop a picture to a fixed size

imagecrop.sh

#!/bin/bash
# ~/croptest is our work dir, ~/croptest/img contains test images
cd ~/croptest

EXT="_resized"
SIZES="88x88 88x50 300x172 300x233 300x111"

# delete all remains of previous runs and copy test pics over
rm *.jpg
cp img/*.jpg ./

for SIZE in $SIZES; do
  for IMG in img/*.jpg; do
    IMG=${IMG/img\//}
    OUT=${IMG/.jpg/_${SIZE}.jpg}
    # get image size
    IMG_W=`identify -ping -format '%w' $IMG`
    IMG_H=`identify -ping -format '%h' $IMG`
    if [ $IMG_W -le $IMG_H ]; then
      ## portrait or square, crop from upper third
      TGT_SIZE=(${SIZE//x/ })
      #TGT_W=${TGT_SIZE[0]}
      TGT_H=${TGT_SIZE[1]}
      ## just scale and calculate with new sizes
      convert $IMG -fuzz 1% -trim +repage -resize ${SIZE}^ ${OUT}
      #IMG_W=`identify -ping -format '%w' $OUT`
      IMG_H=`identify -ping -format '%h' $OUT`
      REST_H=$(( $IMG_H - $TGT_H ))
      TOP_OFFSET=$(( $REST_H / 3 ))
      ## now crop
      #echo "$IMG is portrait, resized as $SIZE = (${IMG_W}x${IMG_H}) top crop: $TOP_OFFSET"
      convert ${OUT} -crop ${SIZE}+0+${TOP_OFFSET} +repage ${OUT}
    else
      ## landscape
      convert $IMG -fuzz 1% -trim +repage -resize ${SIZE}^ -gravity center -extent ${SIZE} ${OUT}
    fi
    #OFFSET_TOP = identify -ping -format '%[fx:(h-233)/3]' $IMG
    ## see http://www.imagemagick.org/script/fx.php
  done
done