Abstract: An efficient technique for calibrating a scanner relative to a particular colorant set having N primary colorants. Once the scanner is calibrated, the scanner's device-dependent tristimulus values for an arbitrary color are transformed to a device-independent representation of the arbitrary color in a computationally efficient manner. The technique exploits the fact that the color space defined by the primary colorants can be advantageously partitioned, with each partition being represented by a transformation matrix that accurately characterizes the transformation for that partition of the space. The partitioning is characterized by a set of M key colors (in a specific embodiment, M=2N), each of which defines a boundary between adjacent partitions.

Abstract: A desktop color measurement system that includes an instrument capable of making color measurements. The system includes a host computer and a digital color sensor (DCS) in communication with the host computer. The DCS includes optical elements for making spectral measurements, and control electronics for controlling the optical elements. In a specific embodiment, the DCS is dedicated to the mechanics of acquiring the raw data. The host computer, which may be a personal computer, performs all the calculations needed to convert raw measurement values into spectral data and other color representations such as tristimulus values and density. This also allows the system to function as a calorimeter and a densitometer as well as a spectrophotometer. The DCS control circuitry includes non-volatile writable storage for information obtained during a factory calibration procedure, which information allows the user to recalibrate the DCS in the field.

Abstract: A target output device such as a printer is characterized in a manner that primary colorant amounts can be determined on the basis of a pair of chromaticity coordinates in a chromaticity space having a pair of chromaticity coordinates that span hue and chroma (saturation) and a luminance correlate (monotonic function of luminance). Lightness (or darkness) of the colors is handled largely independently. This makes it possible to store the colorant information in a two-dimensional table indexed by chromaticity coordinates. The information in the table is for colors that are characterized by the highest luminance that the target printer is capable of rendering for a given chromaticity (hue and chroma).