Color Measurements of Prints of Varying Hue and Gloss Using Spectrophotometers with Three Different Geometries

Colorimetric measurements of 54 Pantone+- printed color samples, half coated and half uncoated stocks, and covering a wide range of hues, were made with a variety of spectrophotometers. The instruments chosen were both bench and portable types having 0/45, 45/0 and D/8 (sphere) geometries. In all, a total of 702 measurements were made and 3,510 color values were recorded. Some differences were observed between 0/45 and 45/0 geometries, despite the presumed interchangeability of these two optical systems. This may be at least partly due to different optical paths and different manufacturers' instruments. As expected, the D/8 (sphere) geometry differs significantly from the other two. These differences also vary with both hue and surface gloss so that constant correlation factors cannot be used to compare the observed values. The agreement between spectrophotometers of the same manufacturer and geometry was generally good. However, some differences were observed for spectrophotometers having the same geometry made by different manufacturers. This study shows that when colorimetric data is to be compared in different laboratories, it is essential that spectrophotometers having the same geometry be used. If they are not, it is important to be aware of the type and magnitude of the differences that do exist as demonstrated in this paper. This study shows that when colorimetric data is to be compared in different laboratories, it is essential that spectrophotometers having the same geometry be used. If they are not, it is important to be aware of the type and magnitude of the differences that do exist as demonstrated in this paper.