| 摘要 |
An improved color correction apparatus for improved color printing in a subtractive color printing system is disclosed. The disclosed apparatus utilizes an optimized three-dimensional look up table of pigment density values addressed by primary color values. The look up table is created by printing a plurality of pigment bars in response to known input density signals to a laser beam for each of three color pigments used in the system. Each of these sets of bars is subsequently scanned by the input scanner to determine the spectral content of the resultant bars and thus create a plurality of color pigment values corresponding to the spectral content of each bar for each color which is a complementary color of one of the pigments. These characteristics are used to calculate the spectral content of an actual printed image generated in response to an image generated by an input triplet to the system. Numerical methods are used to alter the pigment signal outputs, subsequently recalculate the spectral content of an actual image, and to repeat these steps until the error between the spectral content of an image pixel from the scanner and the spectral content of the reproduced printed image is minimized. In the resultant apparatus, input signals derived from the scanner are used to directly address the look up table and the data stored in the look up table directly drives a laser source in a laser-based electrophotographic print engine. The look up table thereby compensates for all non-linearities between the laser intensity modulator input signal and the final fusing process and further compensates, to the extent possible, for spectral impurities in the toner pigments used.
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