Abstract: A color chart is constructed by defining a reference color and specifying a range of colors from the reference color, where each color in the range is spaced from any other color by integral multiples of a preselected color difference value, such as at least one CMC value. One or more colors of the range are displayed in a form that can be visually perceived by a user, such as displaying the color(s) on a computer monitor or printing the color(s) on one or more sheets of paper. The method allows color charts to be prepared that lend themselves to an orderly, objective identification of the colors.

Abstract: There is disclosed a method for preparing a color chart comprising the steps of defining a reference color, specifying a range of colors from said reference color, each color being spaced by integral multiples of a preselected color difference value from any other color, the range spanning the color space between the reference color and some other color.

Abstract: A method for making a dye mixture to produce a target colour on a given substrate, comprising the steps of: ?a) measuring reflectance values RT(?i) of the target colour at a plurality of wavelengths ?i=1, 2 . . . n; b) measuring reflectance values Rs (?i) of the substrate at the same wavelengths ?i; forming a set of concentrations cj of M dyes in the calculated concentrations; the database having been compiled by aa) making dyeings of combinations of the dyes Dn at different concentrations; bb) measuring the reflectance values R of the dyeings at different wavelengths; cc) defining a function f(R); dd) defining a relationship between f(R) and c involving constants g and k; and ee) for each dye Dn determining constants gn, kn, such that the calculated values for f(R), c, gn kn approximate closely the measured values.

Abstract: There is disclosed a method for preparing a colour chart comprising the steps of defining a reference colour, specifying a range of colours from said reference colour, each colour being spaced by integral multiples of a preselected colour difference value from any other colour, the range spanning the colour space between the reference colour and some other colour.

Abstract: A method for making a dye mixture to produce a target colour on a given substrate, comprising the steps of a) measuring reflectance values RT(&lgr;i) of the target colour at a plurality of wavelengths &lgr;i=1, 2 . . . n; b) measuring reflectance values Rs(&lgr;i) of the substrate s at the same wavelengths &lgr;i; c) forming a set of concentrations cj of M dyes, j=1, 2, . . . M from a database of N dyes Dn, b=1, 2 . . . N with associated constants gn, kn; d) making dye mixtures using the M dyes in the calculated concentrations; the database having been compiled by aa) making dyeings of combinations of the dyes Dn at different concentrations; bb) measuring the reflectance values R of the dyeings at different wavelengths; cc) defining a function f(R); dd) defining a relationship between f(R) and c involving constants g and k; and ee) for each dye Dn determining constants gn, kn, such that the calculated values for f(R), c, gn, kn approximate closely the measured values.