White balancing method

A method for white balance of an optoelectronic color scanner element of a color scanner device for pixel-by-pixel and line-by-line scanning of a color original illuminated by a scan light source for trichromatic splitting of scan light modulated with optical densities of scanned picture elements and limited by a scan diaphragm into color components for each color channel and for conversion of the color components into color signals with a light/voltage transducer in every color channel, comprising the steps of:

• predetermining a white level UWP for each color channel;
• measuring optical densities DWP of three color components of a white point of the color original which is a brightest location;
• calculating rated voltage values USOLL that the actual voltage values should reach given optical density “zero” of the color original for the three color components from the measured optical densities DWP of the white point of the color original and from said predetermined white levels according to the equation:
• USOLL=UWP×10 exp. [DWP];
• simulating with a light source scan light that represents the optical density “zero” of the color original;
• converting the scan light representing the optical density “zero” with said light/voltage transducer into color signals as actual voltage values for the individual color components;
• comparing the actual voltage values to the rated voltage values USOLL;
• and
• setting and holding constant gains of the light/voltage transducer in the three color channels for a duration of the scanning of the original such that the actual voltage values that are generated given the scan light representing the optical density “zero” of the color original are equal to the calculated rated voltage values USOLL, and as a result thereof, the color signals of the white point of the color original acquired in the later original scanning correspond to the predetermined white levels UWP.