Infrared image processing
After the pseudo-static sequence is obtained, principal component thermography (PCT) is applied in the reconstructed sequence. PCT, originally proposed by Rajic in Ref. [16], extracts the image features and reduces undesirable signals. It relies on singular value decomposition (SVD), which is a tool to extract spatial and temporal data from a matrix in a compact manner by projecting original data onto a system of orthogonal components known as empirical orthogonal functions (EOF). The first EOF will represent the most important characteristic variability of the data; the second EOF will contain the second most important variability, and so on. Usually, original data can be adequately represented with only a few EOFs. Typically, an infrared sequence of 1000 images can be replaced by 10 or less EOFs.