extract an image's elements by gd

[Tontonq Tontonq]

Hi!
as first i want you look at this image http://i56.tinypic.com/2zic001.png

i can read all pixels , make picture black and white,add length of black
pixel's to array like (from 300x 20y to 320x to 20y).

I can dump coordinates blue square as easily but i cant say this for yellow
ellipse.

So there are 2 questions
How can i export an image's a part that i know x,y coordinates and save it
as image
All of you should know mspaint's free-form select,for able to export yellow
ellipse i will need something like that so how can i export an image's a
part like at mspaint's free-form select function

are these possible with gd library?