Abstract: The present invention provides a method and apparatus for accurately matching colors. The color matching system includes a host computer and a color input device in communication with the host computer. Preferably the color input device is capable of obtaining spectral data, such as that obtained using a spectrophotometer. The host computer includes a color library, a color management system, a monitor, and a user interface. In one aspect of the invention, the user selects a target color, a color library to use for matching, a color distance tolerance, and a light source under which the colors are to be matched. The target color is compared to the colors in the library and the color or colors in the library that are within the specified color tolerance are reported. In a second aspect of the invention, the user selects a color and two illuminants. The color under each of the two illuminants is compared and the color distance between the two is reported.

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).

Abstract: A computer imaging system for calibration of scanners and printers. A calibration image is stored and manipulated as desired, and printed out as a resultant calibration picture. The resultant calibration picture is input to the system to create a resultant calibration image. A comparison is made between the original calibration image and the resultant calibration image, yielding calibration data indicating the distortion introduced by the hardware and software combination used in the calibration process. The calibration data is then used in a correction stage wherein a picture is input to the system, anti-distorted utilizing the calibration data, and an output picture provided with the anti-distorted data causing the output picture to appear substantially identical to the input picture. Alternatively, the calibration data is used together with a second set of calibration data generated by comparing an input calibration picture with known accurate data values corresponding to the calibration picture.