Method and device for controlling the chromaticity on the surface of a body

摘要

The subject-matter of the invention is a method for generating colour content signals with the aid of which the chromaticity of a surface region of an object can be detected independently of fluctuations in illumination. Radiation emanating from a surface region (1) of the object (2) is decomposed by filtering into three colour contents, which are converted into electrical colour content signals. The colour content signals are combined to form an aggregate signal which, as actual value of a controlled variable, is compared with an adjustable desired value in order to form a system deviation. The magnitude of all three colour content signals is modified to the same extent in accordance with the system deviation for the purpose of reducing the system deviation to zero or to a very low value. At least one colour content signal is multiplied by a coefficient which corresponds to the quotient formed from the colour content signal and the magnitude of the parameter for a prescribed desired value with which the product of the colour content signal and coefficient is compared in order to form a system deviation. The magnitude of the parameter is modified for the purpose of reducing the system deviation to zero or to a value close to zero.