A method is presented for deriving a conversion from reflectance spectra to a convenient intermediate form introduced as LabPQR. LabPQR is designed for use within a spectral color management system as an interim connection space (ICS) between a reflectance based profile connection space (PCS) and output device digit counts. The LabPQR ICS makes use of a spectral encoding that explicitly incorporates colorimetry. The initial three dimensions of a LabPQR ICS provide a colorimetric representation of reflectance spectra under an illuminant. Additional dimensions define spectral corrections that allow inverse transformation to approximately the original spectra. Consistent with a previously defined spectral color management transformation chain, the PQR dimensions of the ICS can be optimally formulated to suit any specific output device's spectral rendering capabilities. After describing a method for distilling spectra into, and reconstituting spectra, from LabPQR coordinates, several sample transformations are demonstrated using various output devices. Visualizations follow of some sample LabPQR gamuts. Observations are made, and from these observations, a possible method for performing spectral gamut mapping is proposed. Current methods of color management (specifically using ICC profiles) are discussed relative to LabPQR visualization. In conclusion, proposals are made for future research and possibilities. (C) 2006 Society for Imaging Science and Technology.
