[Insight-users] Parametric vs. Non-parametric image registration?

[Lodron, Gerald]

Parametric means that you can model the transformation via a formula which is only dependend on a few parameters, e.g.

f(x,y) = (x',y') = (x,y) + (tx, ty) 

Here the parameters of that "translation transform" are tx and ty.


Nonparametric means that the transformation cannot be represented by such an formular, you need an explicit deformation vector for EVERY pixel. That is for an 2D MxN image a MxNx2 deformation field. It should be clear that a parametric transaformation is much easier to invert and smaller to save. 



-----Ursprüngliche Nachricht-----
Von: insight-users-bounces at itk.org [mailto:insight-users-bounces at itk.org] Im Auftrag von motes motes
Gesendet: Dienstag, 02. Februar 2010 09:14
An: Insight Users Mailing List
Betreff: [Insight-users] Parametric vs. Non-parametric image registration?

The terms Parametric and Non-parametric Image registration are used in many articles but what is the exact difference?

I know that optimizing a deformation field using eg. B-Splines is called parametric (the coefficients/parameters of the deformation vectors are optimized).

But what are equivalent examples of non-parametric methods?
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