Novel accuracy test for multispectral imaging systems based on ΔE measurements

Abstract

In the printing industry, multispectral line scan cameras are being applied with increasing frequency in print inspection. This field of application requires highly accurate camera systems. In this article, we describe a novel approach to determining the accuracy of multispectral measurements recorded by line scan cameras. The approach is based on Bayesian statistics and paves the way for inline applications. Our approach uses the distribution of color distances, as expressed by Δ E values, that arise when the reference color spectra of a color chart are compared with corresponding spectra reconstructed from the measured camera responses of observed color patches. By means of 18 Δ E values originating from a color control strip, our approach provides an accuracy evaluation of multispectral imaging systems with line scan technology. To demonstrate this, four scenarios are considered in which the multispectral imaging system is used with different measurement accuracies. It is shown that the imaging system in these cases can be reliably characterized with respect to the quality of the multispectral measurements.