Patent ID: 7110142
Filing Date: 2006-09-19
Classification: G03G,H04N

Abstract:
1. A method of obtaining marking substrate area coverage information, comprising: obtaining a base reflectance of an unmarked portion of a marking substrate; obtaining a reference reflectance of a reference marked patch of the marking substrate at substantially complete coverage; obtaining a target reflectance of a target marked patch of the marking substrate; and obtaining an estimated marking substrate area coverage ĉ of the target marked patch by a least squares algorithm, based on the base reflectance, the reference reflectance and the target reflectance, using a Neugebauer model of the form where and c is the actual marking substrate area coverage, where λ 1 , λ 2 , . . . λ N represent the wavelengths at which reflectance values are measured, r 1 (λ) is the spectral reflectance of the base color of the marking substrate, r 2 (λ) is the spectral reflectance of a marked patch of substantially 100% area coverage, r(λ) is a predicted spectral reflectance corresponding to a marked patch under analysis, n is a Yule-Nielsen correction factor, and N is a number of measured wavelengths of visible light, and wherein the least squares equation is defined by where T indicates a matrix transpose.