Building a simple GUI for image analysis program

[Federico Bravo <fedebravo iol it>]

Hello everybody. I am really new to this list, so please forgive me if I
post questions that have been already discussed. I am writing an image
analysis program: it definitely needs a GUI capable of some very
standard features such as zooming and area selection on pictures,
basically. I am thinking about writing the GUI with GTK, but maybe a
GIMP plug-in could be easier ( althaugh I do not know if interactive
plug-ins can be written).   What  I generally do when I am learning a
language is to try and find a simple program that has similar features
and understand how it works, so please tell me if I can find some simple
code on this ( I just gave a look at GIMP source but it is way too
complex for me to get into it). Maybe there are other libraries ( e.g.
ImageMagick ) that could suit my needs better.  Since I am just
beginning I would like to be pointed into the right direction.
Any suggestion will be really appreciated.
Federico Bravo.