HOWTO batch processing images on linux or mac osx

#  batch enhance images or batch making thumbnails

for file in *.jpg; do

  convert -enhance -equalize -contrast $file "${file%.jpg}_new.jpg"

done

# other options calling convert

#  convert -auto-gamma -auto-level -normalize original.jpg improved.jpg

#  convert dragon.gif    -resize 64x64  resize_dragon.gif

# ref:  http://www.imagemagick.org/Usage/resize/