An improved approach of mutual information based registration for medical images

Mutual information stems from communication theory, which is commonly used as similarity measure in the field of medical image registration. This approach works directly with image data; no pre-processing or segmentation is required. But calculating the mutual information of images needs a large amount of computation, which in some respect restricts its application. In this paper, by doing some processing on the reference image before the registration, we changed the way of calculating the mutual information to reduce the computation. The result of the experiments shows that the accuracy of registration does not change significantly, whereas the time of calculating the mutual information is decreased significantly.