You may encounter this error when usingOpenCV
[http://opencv.willowgarage.com/wiki/]withPython bindings,while trying to use
the rectangle structure.
Here is an example :
{% highlight python %}
!/usr/bin/env python
import cv
img = cv.LoadImage("test.jpg")
dims = cv.GetSize(img)
roi = [0, 0, dims[0] / 2,