The invention relates generally to methods of monitoring and controlling the processing of blood and blood samples, particularly the separation of blood and blood samples into its components. In one aspect, the invention relates to optical methods for measuring two-dimensional distributions of transmitted light intensities, scattered light intensities or both from a separation chamber of a density centrifuge. The method may include performing first and second measurements of an operating condition; analyzing the first and second measurements using a predictive data analysis algorithm; comparing the predicted operating condition to a desired operating condition; and adjusting at least one setting.