ABSTRACT
This chapter deals with a relatively new direction in image processing that proves to be of high importance in many areas, not just in medical applications—obtaining qualitatively new information by combining image data from several different images. The most common and obviously clinically needed is the mere image registration in its many variants: intramodality registration and intrapersonal registration on one side, and intermodality registration and interpersonal registration on the other. Registration also may be the first step of more complex processing leading to the automatic narrower-sense image fusion serving to derive new images. The images to be fused are usually distorted geometrically, for different and often combined causes. The crucial step that must precede fusion is thus to align the data of the to-be-fused images so that the corresponding image features are identically positioned in the image matrices; this procedure is denoted as image registration.
