There are two softwares here.

One allows you to edit a file describing where faces are in the picture,
which we call gzv.

The other one allows you to show the picture, zooming in and out between
faces, which we call movie.

To run gzv, you will need PyGTK, which, in Debian, is installed by the
python-gtk2 package. Then, run it with python gzv.py.

There is a sample project file named project, with the Debconf8 picture
and a dots file.

To build movie, you will need GTK+ and GDK-Pixbuf development files. In
Debian, just install libgtk2.0-dev. Then type make.

To show the picture, just give as parameters to the movie program the
picture and the dots file.