Abstract

Color gamut volume (CGV) is an important characterization method to quantify the range of colors that a printing press can reproduce, based on the combination of press, substrate, and ink and measured using color measurement devices. Dissimilar color measurement tools and procedures can introduce variability that may complicate the comparison of the resulting color gamuts. This study investigates how different sampling and instrument selection affect CGV estimation. Using a standard CMYK test chart (ISO TC1617), prints were made on two paper substrates of different basis weight and surface properties using an electrophotographic digital press. The X-Rite iSis 2 XL, (revision A) and an XRite i1iO table with i1 Pro 3 (i1iO 3) were used to measure the printed charts. Measurements were collected in two ways: (1) repeated measurements of a single sheet to evaluate instrument precision, and (2) single measurement of multiple sheets to assess product variation. The resulting color gamuts were computed in CIE L*a*b* space to create ICC profiles and CGV was estimated using Chromix ColorThink Pro, version 3.09 using Microsoft Windows 11 Pro. The i1iO 3 consistently reported a larger gamut volume than the iSis 2 XL (on the order of ~3–4% higher), a difference found to be statistically significant. Despite this offset between devices, both instruments demonstrated high repeatability: the differences between ten-sample averaged volumes and one-sample volumes were <1% on average for each device. Certain individual color patches exhibited measurement variation (>1 ΔE*ab) between repeated scans, particularly in darker tones, but these had minimal impact on the overall gamut volume. The heavier, coated 120 lb cover stock yielded a ~9% greater gamut volume than the lighter 70 lb text stock, highlighting that substrate characteristics do affect color gamut capacity. Overall, our findings underscore the importance of measurement standardization and multi-sample averaging for reliable CGV analysis. The results highlight the need for standardized measurement practices and the use of multisample averaging to ensure accurate and reliable CGV evaluation. The study concludes with recommendations for improving reproducibility, including instrument certification, clear reporting of measurement conditions, and the need for the development and adoption of a Gamut Comparison Index (GCI), an ISO compliant metric intended for both research and industry application.