A process of bringing first and second data sets into registration/conformity with each other. A plurality of candidate data sets are provided, each being a differently shifted or distorted form of a reference data set. Each of the first and second data sets and the reference data set being a representation of a particular physical object. The process compares respectively the first and second data sets with each of the candidate data sets and in dependence on the comparisons to determine respective first and second transformations that bring into registration or conformity with each other the reference data set and a particular candidate data set out of the plurality of candidate data sets which provides a best match with the respective first and second data sets, and brings the first and second data sets into registration/conformity with each other in dependence on the first and second transformations.