Product appearance can be a critical component in the determination of final quality assessment. Basic optical measurements are made to determine whether the product color, or gloss attributes meet specified standards. Comparison of product to standard usually occurs at the end of the process. The objective of this paper is to show how and when appearance- measuring devices, used to measure appearance in the steps of a process, can keep process variables in check.
Thomas J. Mabon,
"Optically based methods for process analysis", Proc. SPIE 1681, Optically Based Methods for Process Analysis, (14 August 1992); doi: 10.1117/12.137735; https://doi.org/10.1117/12.137735