mogrify -resize 640 *.jpg
convert -resize 750×500 -quality 80% *.jpg
convert -verbose -resize 600×900 -comment "Comments ftw"
 
for x in $(ls *.JPG); do 
  convert -verbose -resize 600 -quality 80% -comment "www.newioit.com.au" $x res$x; 
done

convert source.bmp -colors 2 -depth 1 -monochrome destination.bmp