Comment on Facial expression recognition based on two-dimensional discriminant locality preserving projections [Neurocomputing 71 (2008) 1730-1734]
In this note, we show that the mathematical formulation of the two-dimensional discriminant locality preserving projections (2D-DLPP) proposed in the paper [R. Zhi, Q. Ruan, Facial expression recognition based on two-dimensional discriminant locality preserving projections, Neurocomputing 71 (2008) 17301734] is not very sound. The rigorous version is thus given. We also point out that 2D-DLPP can be viewed from the perspective of the discriminant locality preserving projections (DLPP).
two-dimensional discriminant locality preserving projections (2d-dlpp) two-dimensional locality preserving projections (2d-lpp)