This document reviews various approaches for face recognition. It begins by describing challenges in face recognition related to scale, pose, illumination, and disguise. It then discusses principal component analysis (PCA) and local discriminant analysis (LDA), which are appearance-based approaches, as well as local binary pattern (LBP) and local ternary pattern (LTP), which are texture-based approaches. PCA uses eigenfaces to represent facial features while LDA aims to preserve discriminating information between classes. LBP and LTP extract texture features from facial images for recognition. The document concludes LDA generally provides better accuracy than PCA for whole-face recognition, while LTP performs better than other methods for texture-based recognition as it is more