To use theses scripts, you must install imagemagick and inkscape. 
As in Nautilus (in Ubuntu 13.04), you can't launch a script with a double clic on it, it's recommanded to install the command "launch a terminal here" in the right clic. 
sudo apt-get install imagemagick inkscape

for those of you who are running Ubuntu :
sudo apt-get install nautilus-open-terminal
