ABSTRACT
The National Library of Medicine Insight Segmen ta tion and Registration Toolkit, sh ortened as th e
Insight Toolkit (ITK), is an open-source software toolkit for performing registration and segmenta-
tion. Segmenta tion is the process of identifying and classifying data found in a digitally sampled
representation. Typica lly the sampled represen ta tion is an image acquired from such medical instru-
mentation as CT or MRI scanners. R egistration is the task of aligning or developing correspondences
between data. For example, in the medical environment, a CT scan may be aligned with a MRI scan
in order to combine the information contained in both.
ITK is a cross-platform software. I t uses a build environment known as CMake to manag e platform-
specific project generation and compilation process in a p la tform-in depend e nt way. ITK is imple-
mented in C++. ITK’s implementation style emp loys generic progra mming, wh ic h involves the
use of templates to generate, at compile-time, code that can be applied generically to a ny class or
data-type that supports the o perations used by the template. T he use of C++ tem plating means that
the code is highly efficient and many issues are discovered at compile-time, rather than at run-time
during program execution. It also means that many of ITK’s algorithms can be applied to arbitrary
spatial dimensions a nd pixel types.
An automated wrapping system integrated with ITK generates an interface between C++ and a high-
level programming language Python. This enables rapid prototyping and faster explor ation of ideas
by shortening the edit-compile-execute cycle. In addition to automated w rapping, the SimpleITK
project provides a streamlined interface to ITK that is available for C++, Python, Java, CSharp , R,
Tcl and Ruby.
Developer s from around the world can use, debug, maintain, and extend the software because ITK
is an open-sour c e project. ITK uses a mod el of software development known a s Extreme Pro gram-
ming. Extreme Programming collapses the usual sof tware development methodology into a simu lta-
neous iterative process of design-implement-test-relea se. The key features of Extreme Progr amming
are communication and testing. Communication among the members of the ITK community is wh a t
helps manage the rapid evolution o f the software. Testing is what keeps the software stable. An
extensive testing process supported by the system known as CDash measures the quality o f ITK
