Method and apparatus for gloss measurement with reference value pairs

An apparatus for measuring the gloss of a surface comprising:

• at least one light source projecting light in the direction of a surface having a characteristic gloss being measured;
• at least one light-sensitive sensor receiving light reflected from the surface and converting the reflected light into a measured electrical signal value;
• storage means storing a computer program for computing the characteristic gloss of the surface from the reflected light and storing at least five reference value pairs, each reference value pair consisting of a reference characteristic gloss value and a corresponding reference electrical signal value respectively produced by the apparatus from a reference surface having a known characteristic gloss;
• comparison means for comparing a measured electrical signal value with the reference electrical signal values and forwarding to the calculating means at least two reference characteristic gloss values having corresponding reference electrical signal values respectively greater and less than the measured electrical signal value;
• calculating means for calculating a characteristic gloss value for the surface from the measured electrical signal value and the reference electrical signal values respectively greater and less than the measured electrical signal value by execution of the computer program;
• and
• display means for displaying the calculated characteristic gloss value.