The development of a connectionist expert system for compensation of color deviation in offset lithographic printing

The offset lithographic printing process requires the operator to make appropriate and timely on-line adjustments to compensate for color deviations from the desired print. An operator acquires proficiency by working on the same machine over a period of several years; thus he is able to apply adjustments according to its specific characteristics. It was found that this machine-specific knowledge consists of articulated and unarticulated knowledge. A connectionist representation was designed to map the observable variables to the operator's adjustments; while a forward chaining expert system was developed to represent the operator's articulated knowledge. A weight-based conflict resolution technique was constructed to dynamically update the knowledge base. This paper begins by presenting the press characterization problem. Then the development of the system is described. Finally, an analysis of results that cover all possible categories is documented. (C) 1999 Elsevier Science Ltd. All rights reserved.