SUMMARYThe paper investigates PDE-based dynamic phenomena for comparing objects and introduces a spatiotemporal non-linear wave metric. This metric is capable of comparing both binary and grey-scale object pairs in a parallel way. Spatio-temporal waves are initialized and controlled to explore the quantitative properties of objects. In addition to spatial data, even 'hidden', time-related information is also extracted and used for evaluating differences and similarities. The detailed analysis of the proposed metric shows that this wave-based approach can outperform well-known metrics such as Hausdorff and Hamming metrics in selectivity and sensitivity. The approach in question can be efficiently implemented on massively parallel architectures, e.g. on Cellular Neural/Non-linear Networks (CNN), providing solutions either for real time applications.