The Role of Scale Adjustment in Color Change Evaluation

The aim of this research work was to assess the influence of dierent scale adjustment conditions on both color measurement and color dierence quantification and, in particular, to determine the best procedure to follow for a high-reliability protocol. This issue is very important in the Cultural Heritage field and, above all, in color measurement, which is carried out at dierent times during conservation and restoration campaigns or during archaeological excavations. Color change evaluation, performed by way of spectrophotometric measurements under dierent scale adjustment procedures on selected samples represented by colored reflectance standards and colored paintings, aimed to obtain results not only on ideal samples (certified standards) but also on real case studies (paintings). The study was conducted by focusing on the coordinates of the CIELAB color space and, in particular, on the calculation of the DE*ab quantity. The results show the introduction of nonsystematic variation with dierent scale adjustment procedures independent of materials and hue.