Characterization of Ghosting Defects in Electrophotographic Printers

Ghosting is a common print defect in electrophotographic printing. Printers experiencing ghosting defects show repeated images (residual images) of previously printed contents in the paper process direction. Detecting the residual image (ghost) location and contrast provides necessary information about the ghosting source and severity. In this paper, we present a new system for detecting and quantifying the ghosting defect. It includes a design for a printed test pattern to emphasize the ghosting defect and facilitate further processing and analysis. Wavelet filtering and a template matching technique are used to detect the ghost location along and across the scanned test pattern. A new metric is developed to quantify ghosting based on its contrast, shape, and location consistency. Experimental results on 31 samples of various types of ghosting showed 0.95 correlation between the proposed method´s ranking and experts´ visual ranking.