| 摘要 |
A method of manufacturing a soil or wear test feature on a document of value is provided. The method comprises designating an area of the document of value for soil or wear testing and measuring an optical characteristic which is affected by the presence of soil or wear of the designated area on the document of value, or of the same area on an identical document of value. The measured optical characteristic is encoded to generate corresponding optical characteristic data and the encoded optical characteristic data is associated with the document of value by means of a machine readable element provided on the document of value. Also provided is a method of detecting soiling or wear of a document of value, comprising measuring an optical characteristic which is affected by the presence of soil or wear of a designated area on the document of value; reading data from a machine readable element provided on the document of value to retrieve encoded optical characteristic data generated from previous measurement of the optical characteristic of the designated area, or of the same area on an identical document of value; and comparing the measured optical characteristic with the encoded optical characteristic to identify any difference therebetween, a difference being indicative of soiling or wear of the document of value. |
