Editing Motion estimation (section)

===Additional note on the categorization===
It can be argued that almost all methods require some kind of definition of the matching criteria. The difference is only whether you summarise over a local image region first and then compare the summarisation (such as feature based methods),  or you compare each pixel first (such as squaring the difference) and then summarise over a local image region (block base motion and filter based motion). An emerging type of matching criteria summarises a local image region first for every pixel location (through some feature transform such as Laplacian transform), compares each summarised pixel and summarises over a local image region again.<ref>Rui Xu, David Taubman & Aous Thabit Naman, '[https://ieeexplore.ieee.org/abstract/document/7370941/ Motion Estimation Based on Mutual Information and Adaptive Multi-scale Thresholding]', in IEEE Transactions on Image Processing, vol. 25, no. 3, pp. 1095-1108, March 2016.</ref> Some matching criteria have the ability to exclude points that do not actually correspond to each other albeit producing a good matching score, others do not have this ability, but they are still matching criteria.