Color calibration for critical color proofing in the graphic arts is a two-fold process. The first step in the process is to select a technology that closely resembles the fundamental spectral behavior of colored pigments used in the printing industry. The second step in the process is to optimize the parameters by which the pre-press proof is made in order to achieve the best visual match between the proof and the printed image. In the case of digital proofing, there are two sets of parameters which generally can be optimized. The first set of parameters pertain to the densities and hence the colorimetric values of the solid primaries (YMCK) as well as secondaries (RGB) and tertiaries (3/C). The second set of parameters pertain to the tone response, and are generally in the form of one dimensional look-up tables. If the technology chosen is very dissimilar to the spectral properties of printing inks, it may be necessary to use 3 and 4 dimensional color transformation. While this approach can achieve good color matching results for one illuminant condition, it begins to negate the value of high resolution halftone proofing, since `false dots' begin to appear in the pre-press proof which do not occur in the halftone film.