Application of the second derivative of the Kubelka–Munk function to the semiquantitative analysis of Roman paintings

In the present survey, we have analyzed Roman paintings in two rooms in a villa at El Ruedo (Almedinilla, Córdoba, Spain). We used different techniques and procedures, such as X‐ray diffraction and diffuse reflectance. We established parameters that define colours in every international system. The diffuse reflectance techniques allowed us to identify the pigments, emphasizing that their mixtures are usually based upon a single chromatic pigment.