DIGITAL IMAGE COLORIMETRY OF ARCHAEOLOGICAL EARTHENWARE UNDER DIFFERENT LIGHTING SOURCES

This study investigated the effect of lighting sources on the smartphone colorimetry of 23 ar-chaeological earthenware samples. Comparable RGB and L*a*b* colors were obtained using both fluorescent room lighting and smartphone flashlight in a closed box for most samples, although some showed substantial differences likely due to variations in measurement points. Averaging readings from different areas of each sample could reduce this uncertainty. Using the color values to classify the earthenware, five coarse-paste wares averagely exhibited higher R, G, and L* values than 18 fine-paste wares made of fine-grained clay regardless of the lighting used. The L* is recommended as the parameter of choice, as RGB values substantially varied from one sample to another. In addition to the color parameters, the effect of lighting depends on the samples measured as the variations in average L*a*b* values were smaller for the fine-paste ware.