Color control of printing machine with spectral based color measurement used to determine actual vale of spectral reflectance

摘要

Print carrier/paper (22) has number of elements (24) printed with full and/or half tones. Light is shone on elements and reflected light detected by unpolarized spectrometer (28), moved relative to print carrier, to measure unpolarized spectral reflection values. Detected values are processed by processor unit (32) in control unit by program to convert measured spectral reflection value to corrected spectral reflection value, from which actual value for color feed values are determined. Detector unit (28) unpolarized spectrometer measures unpolarized spectral reflection values to provide to processor unit (32) to convert to corrected spectral reflection value. Corrected spectral reflectance values, or colorimetric values or density values determined from corrected values, are transferred (36) to the machine controller (12) for actual-ideal value comparison to set color feed accordingly.. Independent claims included for measurement device with detector for spectral reflectance values, printing unit.