Orthogonal NPE (ONPE)
X. Liu, J. Yin, Z. Feng, J. Dong, L. Wang, "Orthogonal Neighborhood Preserving Embedding for Face Recognition", IEEE International Conference on Image Processing, ICIP 2007, 2007.
Bilateral Two-Dimensional NPE (B2DNPDE)
J. Liang, C. Chen, Y. Yi, X. Xu, M. Ding, "Bilateral Two-Dimensional Neighborhood Preserving Discriminant Embedding for Face Recognition", IEEE Access, 2017.
Exponential NPE (ENPE)
F. Ran, B. Fang, X. Wu, "Exponential Neighborhood Preserving Embedding for Face Recognition", EICE Transactions on Information and Systems, Volume E101–D, No.5, May 2018.