Fig. 2.

Evaluation procedure. A set of 305 lesions was applied to each of a set of normal brain images, and the resultant artificially lesioned volumes together with the normal images were normalized in three ways: with and without cost function masking, and with the enantiomorphic method. The normalization parameters in each case were used to generate a set of deformation fields, from which displacement fields relative to the normalization of the normal brain images were computed. The displacement fields thus provided an index of the normalization error introduced by the lesion for each method, lesion and subject, thereby allowing us to determine which method minimized the error to the greatest extent. See main text for details.