1. A method of monitoring a process producing a characterizing product, the method comprising the steps of: sequentially capturing multivariate images of the characterizing product, each image consisting of an image array of pixel elements of measured intensity values in at least three wavelength ranges defining the dimensions for the image array; creating a feature vector from said image array; performing a regression method to correlate the feature vector with a characterizing feature of the product; and, creating an output of said characterizing feature for continuous monitoring of the process.