Spectrophotometer inter-instrument agreement on the color measured from reference and printed samples

There are many different color measurement instruments that are used within a printing industry. As with all instruments, there have been trends in their application and design as they have evolved over time. Currently there is a move towards the use of spectrophotometry from densitometry, as the de-facto measurement method. This is being pushed specifically by the application of ISO standards, and print specifications such as ISO 12647 and G7(tm). This paper addresses the issue in the communication of color data between different users where different instruments are used.

Earlier work carried out and presented at TAGA [1] showed that when using densitometry there good agreement between the instruments was when measuring standard reference tiles. However, there was a difference in the measured data between instruments when considering actual printed product. This study evaluated the impact of the different instruments in the industry which has an increased focus on color tolerance levels in the printing environment. The investigation evaluated color measurement repeatability of hand held instruments from a number of different suppliers with different illuminants and filters.

The substrates measured as part of this study were reference standards, unprinted substrates, proof products, and actual printed material. The printed material evaluated included digital, lithographic (coated and uncoated), rotogravure and flexographic. The differences in the CIE L*a*b* color data measured are reported upon.