Colormod

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COLORMOD image analysis

We used the COLORMOD program of modal color analysis on scanned sections of sherds, in order to identify and quantify inclusions and the firing spectrum of the ceramic body. The COLORMOD procedure and software was developed in 2002 by Roberto Cossio and Giacomo Chiari, both at the University of Turin at the time (Chiari later at the Getty Conservation Institute), with the potential of application to the study of pigments, petrography, and ceramics.^{Note 1} In an image, the program separates different chromatic areas based on the pixels’ color, which represent different components of the image. Each cluster of pixels that fall within the same color range (that is, a separate component) is represented by a distinct set of Red-Green-Blue values and occupies a distinct position and serial number within a range of gray shades. Different color clusters are progressively identified, one at a time, resulting in a succession of pictures of the same original image until the entire visual field, or as much of it as meaningfully possible, has been broken down to its different color-coded components. The relative quantity of each component that has been chosen for color analysis is tabulated as a percentage of the total number of pixels in the image. In the case of scanned sherd sections, clusters of chromatically related pixels would represent various inclusions (mineral and organic) and/or other features of the ceramic body, such as pores and cracks, as well as different hues of the firing spectrum (Figure 1; Table 1). Identification of mineral inclusions for analysis was based on the petrographic study of selected sherds (see below).

Figure 1: Scanned section image (cropped) of a Chaff Temper bowl (A16q852p14f190, photo number V23q8533; Phase 5, 2000–1900 BCE), before (a) and after (b) COLORMOD analysis.

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Notes

• Note 1: Chiari and Cossio 2004. An introduction to the program by Roberto Cossio and Massimo Chiari circulated as a letter in 2003, on file with the Mozan/Urkesh Archaeological Project. _{Back to text}