An improved classification system for classifying characteristics of an article into classes of characteristics based on features associated with the characteristics. The system includes a first rule-based classifier that provides rules that embody requirements of selected features so as to together define selected classes. These rules are applied to measured features of an article characteristic to assign one of the selected classes to that characteristic, should the article characteristic meet the feature requirements of one of the selected classes. The system also includes a trainable classifier configured based on a training set of preclassified characteristics, with the trainable classifier connected so as to accept from the first rule-based classifier an article characteristic not classified by the rule based classifier. The trainable classifier assigns one of the training set classes to the unclassified characteristic, should the trainable classifier configuration associate that characteristic with one of the training set classes. A second rule-based classifier can be connected so as to accept classified characteristics from the trainable classifier for making refinement classifications, and a third rule-based classifier can be connected so as to accept unclassified characteristics from the trainable classifier for making classification based on selected classes.