A Study of Optical Brightening Agents (OBA) Correction Methods
Almost all papers contain optical brightening agents (OBA) in process color printing. The colorimetric value shifts toward larger negative b* as the amount of OBA in paper increases. Paper containing OBA creates problems in printing conformance because colorimetric aim points of the printing standards, e.g., ISO 12647, have not been updated. To correct for the measurement differences due to OBA effect, this research printed the IT8.7/4 target on paper with and without OBA under the same printing conditions, measured with a spectrophotometer including UV, and corrected printed color produced by paper with without OBA with a linear correction per ISO 13655 as well as an experimental polynomial model via regression. The results showed that the polynomial method corrects the measurement difference between paper with and without OBA better than the linear correction method. Specifically, 90% of color differences between uncorrected data are 4.5∆E76; the linear method can correct the difference to 2.8∆E76; and the polynomial method can correct the difference to less than 1.6∆E76.
OUYANG Yun, XU Min and YANG Li
Q. H. Tian and R. Chung, "A Study of Optical Brightening Agents (OBA) Correction Methods", Advanced Materials Research, Vol. 174, pp. 346-349, 2011