Measurement of Electrophotographic Ghosting

摘要

Electrophotographic (EP) ghosting is a print defect, manifesting itself as the re-development of a previously printed image. It frequently appears when printing a mid-tone fill immediately following an area of solid fill. Within the mid-tone region, the previously printed solid fill gets imaged again as a ghost. Today, several methods exist that measure ghosting. The most common method is measurement of the difference, in lightness or reflectance, between the ghost region and the background. However, this method does not fully correlate to the perception of the ghost defect. This paper describes a technique that allows for a perceptual measurement of ghosting. The procedure involves measuring several features of the ghost defect using a flatbed scanner. The combined set of features then yields a Ghost Index metric (GI), which correlates with human perception. This metric enables better definitions of product design goals and provides a tangible way for gauging progress towards the design goals.