Determining the document authenticity

It is known that the stroke color of a ballpoint pen changes over time (fades), which means that by the color change of the stroke, you can determine the age of the stroke, and therefore the authenticity of the document. It can be noted that the use of objective colorimetry method is widespread during such examinations. In practice, the spectral method is usually used for determining color and chromaticity coordinates. This method has a high measurement accuracy, but unfortunately, it can not be used directly. This fact is related to the aperture of the studied radiation and the entrance slit of the spectral device. Therefore, stroke dye solutions in colorless solvents are used in practice, which causes other difficulties. This paper describes a slightly different method for determining color coordinates, based on the method of computer colorimetry. This method allows to solve the problem.