Visual method: The most basic method for evaluating color of a pigment is to visually examine the mass tone and tint color of
the pigment under specific illumination and to compare it with a standard physical sample. This method has the limitation that color perception may vary from person to person or under different conditions, such as type of light source and angle of viewing.
Spectrophotometric method: To overcome the limitations of visual methods, a more scientific approach to color quantification has been developed. The International Commission on Illumination (Commission Internationale de l’Eclairage, or CIE) introduced the element of standardization of sources and observer. The CIE also introduced methodology to derive numbers that provide a measure of a color seen under a standard source of illumination by a standard observer. The CIE system has become the international standard for color measurement.