Impact of Instrumental Bandpass on Spectral Quantities in Graphic Arts

Colorimetric quantities calculated from spectral measurement data are essential metrics for assessing color reproduction. ISO 13655, the standard for spectral measurement and calculation in graphic arts, has heretofore specified a nominal spectral bandpass of 10nm for these measurements but has not addressed errors that arise under this condition. A revision of ISO 13655 will now recommend a spectral bandpass of 5nm to minimize the impact of bandpass error on tristimulus calculations.

However, an alternative to using devices with narrower bandpass is to apply "bandpass correction", a subject of much research over the last three decades. The goal of this paper is to illustrate the nature of bandpass errors on graphic arts reflectance data, to review the key approaches for bandpass correction and to present simulations showing the reduction in colorimetric error that can be achieved. It is concluded that available methods for bandpass correction are effective, and should be specified in standards for spectral measurement and calculation.