A new elastic image registration method based on free-form deformation

In order to get the accurate local transformation of images to be registered quickly, a new elastic registration method based on the free-form deformation is proposed. This method adopts the coarse-to-fine strategy: initially estimates the global nonlinear transformation, and then determines the regions with local deformation on the basis of the matching error of each landmark point and refine them. Accordingly, the control lattice resolution in these regions is increased and more accurate registration function is obtained. This process is performed until the errors of the entire landmark points are below the predefined threshold. Using this method, each level approaches the more practical deformation than the former level, which assures the registration transformation is accurate and smooth. The registration experiments for the MRI brain images show the proposed method is an accurate, fast and robust elastic image registration method, especially for the images with complex local deformation.