Colour‐difference measurement: The sensitivity of various instruments compared

Because of the progress in electronic technology and the increasing importance of colour quality control in various branches of industry, over the last decades several colour‐measuring instruments have been developed, each one with its own design features; the lack of standardization among them might be an obstacle to the spread of colour quality control as a means for product qualification. Colour‐difference measurements taken with 11 different models of spectrophotometers [four with 45 (circumferential)/0 geometry and the others with diffuse geometry] were compared with the aim of analyzing their correlation and dispersion. In order to cover different colour‐space regions, measurements were taken on test panels painted with four saturated basic hue (red, yellow, green, and blue) acrylic products gradually modified by adding white or black paint. Basic statistical analyses made on colour‐difference values (ΔE* ab , ΔL*, Δa*, and Δb*) resulted in a high correlation among the examined instruments, but a certain variability, particularly as far as certain hues are concerned.