Hello,
Imagemagick is a very powerfull program to modify picture with a simple comand line.
For example, we can write a script to automatically resize, add a border and watermark to many picture in the same directory.
#/bin/sh
for img in `ls *.jpg`
do
convert $img -resize 20% rez_$img
convert -bordercolor "#000000" -border 2x2 -bordercolor "#FFFFFF" -border 4x4 -bordercolor "#000000" -border 2x2 rez_$img border_$img
convert border_$img -font /usr/share/fonts/default/ghostscript/bchri.pfa -fill white -pointsize 16 -draw "gravity southeast text 10,7 '(c) Vargas Emmanuel http://www\
.crapules.com'" final_$img
/bin/rm -f rez_$img
/bin/rm -f border_$img
done