Halftone banding reduction for a class of electrophotographic systems – Part I: Characterization and modeling

This paper proposes new insights and methodologies that complement existing techniques for characterizing and modeling halftone banding, an artifact of periodic light and dark bands across a printed image perpendicular to the print direction, for a class of electrophotographic (EP) systems, which is commercially known as laser printers. For characterizing banding based on transmission error measurement, specific frequency-domain signal processing, i.e., order analysis, was applied to help identify possible disturbance sources with certain gear components. For characterizing banding based on absorptance measurement on printed images, it was pointed out that a good metric should incorporate appropriate nonlinear operator that characterizes the human visual system. This proposition was supported by simulation results obtained from a three-stage visual model. For modeling banding, a more comprehensive EP model was developed to include transmission parameters such as laser scanning frequency, gear dimension, and angular velocity. Simulation study was performed on the simplified version of the derived model, which demonstrated close correlation between halftone banding and transmission quality. This motivates control of the motor/gear transmission system for reducing banding artifact in EP processes.