  Pooling is essentially an operation from the field of Mathematical
Morphology, with max pooling as a limited special case. The more general
setting of MorphPooling greatly extends the tool set for building neural
networks. In addition to pooling operations, encoder-decoder networks used for
pixel-level predictions also require unpooling. It is common to combine
unpooling with convolution or deconvolution for up-sampling. However, using its
morphological properties, unpooling can be generalised and improved. Extensive
experimentation on two tasks and three large-scale datasets shows that
morphological pooling and unpooling lead to improved predictive performance at
much reduced parameter counts.
