All optical systems suffer from stray light due to undesired reflections plus light scattering from surface imperfections, dust, other particles and similar causes. This unwanted light flux can cause serious errors in imaging colorimetry and densitometry. Although minimizing stray-light error has heretofore required complex and expensive optomechanical scanner designs, simpler designs are sometimes preferred because of cost, or for remote detection applications. In this paper, we show that a color error of ΔEL*a*b* = 10 or more is to be expected due to stray light alone in a simple imaging colorimeter, and that this error may easily be corrected with inexpensive signal processing technology. Line scanners, densitometers, imaging radiometers, and online web-product inspection scanners can also benefit substantially.
Peter A. Jansson, Robert P. Breault, "Correcting Color-Measurement Error Caused by Stray Light in Image Scanners" in Proc. IS&T 6th Color and Imaging Conf., 1998, pp 69 - 73, https://doi.org/10.2352/CIC.1998.6.1.art00015