"Alignment" signifies the process of aligning the optical axes of two cameras. This can be effected in video real-time by means of image localization, as localization of a section of an image in a larger image is termed. An optimal localization procedure consists of filtering in order to decorrelate disturbing parts and of determining the error values or calculating a cross-correlation function. Suboptimal procedures are presented which yield feasible structures. Comparing the procedures shows that the highest localization frequency can be attained by combining standardized correlation with adaptive pre-processing.
"Alignment Through Image Localization By Means Of Adaptive Pre-Processing", Proc. SPIE 0641, Acquisition, Tracking, and Pointing, (1 February 1987); doi: 10.1117/12.964435; https://doi.org/10.1117/12.964435