Today's digital photo-finishing equipment support various input and output devices. In these systems the color management is essential and can greatly benefit from a paper model that predicts the color behavior of silver halide paper.Negative film is an important input channel
for most digital minilabs, such as MasterflexD or Cyra system from Gretag Imaging AG. Typically, a negative film is scanned and digitized. A color-matching algorithm generates normalized, film-independent, and mask-corrected film densities (e.g. EyeTech). As opposed to analogue
laboratories the exposing unit of a digital photo printer does not expose paper through negative film. Instead, normalized film densities are converted to CIELAB colors of an ideal paper using a spectral paper model. From the ‘device-independent’ CIELAB color space the image is
mapped to the appropriate output device. In MasterflexD and Cyrafastprint a common output device is the digital photo-printer using DMD technology. The assumption of an ideal paper prevents us from restricting the gamut of the ‘device-independent’ CIELAB color space
to a particular paper brand. The out-of-gamut areas between the ‘device-independent’ color space, the final print, and the sRGB monitor are kept small to minimize losses in image quality during gamut mapping.The color model is also useful at the output. For output profiling
classical color management tools use measured tristimuli from a large set of colored patches to probe the gamut and to relate CIELAB color values to the corresponding printer RGB values. A spectral model helps drastically reduce the number of required colored patches. In addition, a spectral
model facilitates the description of the gamut boundaries compared to a purely empirical, grid-interpolating method.