Standardisation and control of colour measurement for the graphics and print industry has relied on the use of proofing paper as a substrate to assess print reproducibility via measurement of a CYMK media wedge to ISO 12647-7:2004 AMD 1. Due to inherent chemical instability however, chromaticity of proofing paper may shift due to oxidation and thus discolour. Ceramic colour standards have been used in other industries that rely on colour management for their product requirements and quality control since the introduction of the CCSI Set (Ceramic Colour Standards - Series 1) in 1969 and the current version, the CCSII Set has been in service since 1983. Ceramic colour standards have the advantages of being chemically and colorimetrically stable over time in different environmental conditions.
It is proposed that proofing paper chromaticity can be standardised and controlled for drift using white ceramic standards that are traceable back to national metrology laboratory measurements. Standardisation and control can be undertaken by reflectance measurements in 0:45a geometry defining two sets of colorimetric parameters commonly used in the graphics industry, namely CIE 1931 L*a*b* colour space under D50/2deg standard illuminant and observer and corresponding chromaticity coordinates xyY, to define a set of values of the standard reference.
This will provide Quality Control data for the chromaticity of proofing paper and as such; repeatability and reproducibility via traceable standardisation of common colorimetric parameters. This can be combined with inter-laboratory comparison programs for standard chromaticity measurements of a white standard for spectrophotometers. Expanded uncertainties in accordance with the GUM (Guide to Uncertainty in Measurement) can also be provided for the colorimetric parameters in accordance with ISO 17025:2005 for testing and calibration in order to easily assess the performance of proofing paper against national standards.