This document summarizes several commonly used features for cross-spectral image matching between visible light and thermal images. It discusses how features represent information from different spectrum images for matching. The document reviews features such as local binary pattern (LBP), histogram of oriented gradients (HOG), scale-invariant feature transform (SIFT), Gabor wavelets, discrete cosine transform (DCT) and binary statistical image features (BSIF) that have been used in cross-spectral face and iris recognition with good results. It provides an overview of how these features extract unique characteristics from visible and thermal images to effectively represent the images and enable successful cross-spectral matching.