Motif detection in quantum noise-limited electron micrographs by cross-correlation

The use of cross-correlation to detect randomly positioned low-dose realizations of a motif in an image field is quantitatively evaluated. For both the bright- and dark-field cases, we derive theoretical expressions for the minimum dose allowing detection in terms of motif size, resolution, and contrast. Model computations on simulated low-dose images of a spherical virus particle give results that agree with our theoretical formulas and demonstrate the feasibility of this approach.