The characterization of crystalline aggregates by the crystallographic orientations of their grains and subgrains has become a subject of increasing interest. The information obtained is not only used for the characterization of materials, but also more importantly for the determination of properties. To mention only a few, applications have been found in the areas of fracture analysis, recrystallization, and plastic deformation.Most commonly, crystallographic orientations are determined from Backscattered Kikuchi Diffraction (BKD) in the SEM and from Kikuchi patterns obtained by microdiffraction in the TEM. Since the development of fully automatic pattern analysis routines for the BKD, the SEM based techniques currently finds the most applications. In conjunction with computer controlled stage or beam displacements, the technique is known as Orientation Imaging Microscopy (OIM). In this manner, thousands of diffraction patterns are analyzed automatically within a short time. This leads to a statistical description of the distribution of crystallographic orientations, which sufficiently represent the bulk material.