An efficient method of merging images from electron
crystallographic data has been developed that is several orders
of magnitude faster than the method of phase shift origin search.
The results of this new cross-correlation method are compared
with the phase residual in terms of speed, consistency with
the phase residual method, and the ease of incorporating symmetry
constraints along with the image-to-image merging. The program
is further accelerated by a more efficient sorting procedure.