Analysis of color measurement uncertainty in a color managed printing workflow

Since the recent revision of ISO 12647-2 and ISO 12647-7, specifying the requirements for systems that are used to produce hard-copy digital proof prints, the use of color measurement instruments is even more than before required in the printing industry. Currently, there are many different makes and models of color measurement instruments used in the industry. Therefore, in a modern color managed printing workflow, most of the printing houses use more than one color measurement instrument, typically one instrument in each department (pre-press, press, and post-press). In this paper, a total of nine commercial spectrophotometers are compared in terms of measurement uncertainty, precision and accuracy, repeatability and reproducibility. The BCRA series 2 ceramic gloss tiles are used to confirm the accuracy and repeatability of these measuring instruments according to the manufacturer's standards. We focus especially on inter-instrument and inter-model reproducibility and discuss the effect of instrument calibration and certification. For our experimental setup, four different materials are used, one proof print, one commercial print, and one reference print, along with the BCRA series 2 ceramic gloss tiles. In a color managed printing workflow the use of more than one instrument can impair and complicate the color process control due to the color differences between different measurement devices. The effect of the colorimetric measurement errors due to large inter-instrument and inter-model variability between instruments used in different parts of the workflow (e.g. in the printing house, at the customer's site for inspection, and for certification) is discussed and demonstrated in this paper.