drawing on an image

[Matt Clarkson]

Hi there everyone,
	a quick question.  I am sure that there are many
ways to solve this one, so I was looking for a pointer
as to which is the most convenient path to follow.

Quite simply, if I have a vtkImageViewerWidget, which is
displaying an image, and I want to draw on top of it,
(ie. for image segmentation).

First of all, how can I draw on it?
How can I convert this to geometric primatives (contours)
describing the shape?

Oh yes, what is the difference or purpose of have
both classes vtkTkImageViewerWidget and vtkTkImageWindowWidget?

Many thanks.

Matt

-- 
Computational Imaging Science Group                
Radiological Sciences,                                  
Guy's Hospital                           
London Bridge                       
London                                                                      
SE1
9RT                                                                     
Tel: 0171 955 2380       
Fax: 0171 955 4532  
E-mail: m.clarkson at umds.ac.uk         
WWW: http://carmen.umds.ac.uk/m.clarkson
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