Details:
Summary:
In electronic publishing, it becomes more and more important that the color rendering on monitors and on printing substrates is visually corresponding. This reduces time consuming repetitions and waste of material in the prepress stage and in printing. Different color spaces have to be used for the monitors and the output media. In this paper the RGB color space is used for presenting the colors on the monitors, the CIE-XYZ color space for the calculation and the CMY color space for presenting the colors on the printing substrates. Once a picture from a monitor has to be presented on a printing substrate the color information of every pixel of the picture has to be transformed to the color space valid for the printing process. Three different methods for this data transformation between the two color spaces are explained in this paper. Once a picture from a monitor has to be presented on a printing substrate the color information of every pixel of the picture has to be transformed to the color space valid for the printing process. Three different methods for this data transformation between the two color spaces are explained in this paper. The first method is calculating the transformation for every pixel by a mathematical modell e.g. Neugebauer which is accurate but time consuming. The second method is calculating the transformation for every pixel by a mathematical analytical model with less accuracy but faster then the first method. The third method is using measured color test charts as a lookup table. The transformation for every pixel is done by using the created lookup table. This method is fast for the transformation and its accuracy depends on the density of the lookup table. Six mathematical models were tested in order to get information about the accuracy of the color transformation between the RGB and the CMY color space. Three models work with the well known Neugebauer equations and the other three with first, second and fourth order matrix equations. Deviations of the resulted screen dot sizes calculated by the six models were compared by using two color test charts. In addition the results were also compared with deviations resulted by using the color test charts as low density lookup tables.