The paper presents a family of kernel mean shrinkage estimators. These estimators generalize the ones proposed in \cite{journals/jmlr/FukumizuSG13} and can incoporate useful domain knowledge through spetral filters. Here is a summary of interesting contributions:
1. Theorem 1 that shows the consistency and admissibility of kmse presented in \cite{journals/jmlr/FukumizuSG13}.
2. The idea of spectral kmse (its use in this unsupervised setting) and similarity of final form with the supervised setting.
3. Theorem 5 that shows consistency of the proposed spectral kmse.