Abstract: Printing with a first print engine on a front side of a substrate, and a second print engine on the rear side of the substrate, wherein a first spectrophotometer sensor and a second spectrophotometer sensor are used for spectrophotometric measurements on the blank front and rear sides of the substrate, and producing correction data which represent a deviation of the spectrum representing output signals from the first and second sensors, and wherein a correction derived from the correction data compensates a deviation in the spectral reflectivity of at least one of the front side and the rear side of the substrate. Cross-calibrating the first and second sensors is by processing the spectrum representing output signals of the sensors from identical spectrophotometric measurements.

Abstract: A spectrophotometer diagnosis system and a method for diagnosing a spectrophotometer, wherein at least one test patch is printed in proximity to at least one non-printed substrate patch, at least one value characteristic of the at least one test patch and/or the at least one substrate patch is measured using the spectrophotometer, and at least one diagnostic score for the spectrophotometer is determined based on the at least one measured value in comparison with a reference value.

Abstract: A spectrophotometer diagnosis system and a method for diagnosing a spectrophotometer, wherein at least one test patch is printed in proximity to at least one non-printed substrate patch, at least one value characteristic of the at least one test patch and/or the at least one substrate patch is measured using the spectrophotometer, and at least one diagnostic score for the spectrophotometer is determined based on the at least one measured value in comparison with a reference value.