Subtractive Color Mixing Research Articles

Color Prediction of Union Fabric Considering Mutual Reflection between Yarns

A prediction method of surface color of union fabric from individual color of yarns and weave was established. Thirteen color yarns were adopted as yarn samples, and sixty union fabrics consisted of two colors of yarns were weaved as fabric samples. Kubelka-Munk's law and Lambert-Beer's law were used to predict surface color as theory of subtractive color mixing. Moreover the isomeric matching method was used for making spectral reflection factor in prediction. It is an ideal color matching method that spectral reflection factor of object color is matched with spectral reflection factor of assignment color. The relationship among the density of predicted color(DF(λ)), the density of warp and weft colors(Dwarp(λ), Dweft(λ)) and the area ratio of warp and weft(S, 1-S) could be expressed as follows:DF(λ)=S·Dwarp(λ)+(1-S)·Dweft(λ)In order to reduce the difference between the predicted color and the measured color, the difference between density of warp and weft was considered. As a result, the surface color of union fabric can be predicted accurately.

Color Design and Adjustment of Dichroic Dyes for Reflective Three-Layered Guest-Host Liquid Crystal Displays

ABSTRACT Relationships between properties of dichroic dyes and performances of three layered Guest-Host Liquid Crystal Displays (GH-LCDs) with subtractive color mixing of yellow, magenta and cyan were studied by color mixing simulation. In the case of using the dyes we developed, it was found that the color reproduction areas were as much as 1.6 times larger than in the case of using only commercially available dyes. Performances of our prototype reflective three-layered GH-LCDs were high (the luminous reflectance of the white state was 43%, and the contrast was 5.3), indicating that three-layered GH-LCDs are practical for the display of full-color images.

Color Gamut Boundaries in CIELAB Space

Color gamut boundaries in CIELAB space are determined for two CIE standard observers, CIE 1931 2° and CIE 1964 10°, under two illuminants, D50 and D65, using spectral and optimal stimuli. Computational methods and formulas based on Grassmann's law are given. Two-dimensional projection of the computed color gamut provides the boundary for all possible stimuli, real and imaginary, and is the closest analogue to the chromaticity diagram of the CIEXYZ or CIELUV space. We also discuss reasons of no chromaticity diagram in CIELAB space. This computation leads to the derivation of the most saturated primary colors for block dyes. Two-dimensional gamut projections of several sets of block dyes are then computed under conditions of the CIE 1931 color match functions and illuminants D50 and D65. The validity of the Grassmann's law is examined for additive and subtractive color mixing of block dyes. Finally, color gamut boundaries of two real devices are presented for comparisons.

Filters for color mixing

Sources and prices of good quality plastic color filters are given, as is information about using them for additive and subtractive color mixing.

Creation of Spectral Reflectance Curves from Image Colours for Computer Colorant Formulation

A special algorithm, based on subtractive colour mixing, has been developed to create spectral reflectance data for colours with known CIE tristimulus values. This method is particularly attractive for image colours created on the computer aided design systems (CAD) or colour manipulation systems (CMS). The creation of spectral reflectance data for the image colours allows digital integration of the CMS/CAD systems to the downstream product development system such as computer colorant formulation system. The integration of such systems with other application systems via the Internet or intranet has greatly enhanced its popularity and effectiveness. This paper also evaluates the effectiveness of the proposed subtractive algorithm and compares its performance with a method based on additive algorithm.

Applying the Kubelka-Munk Equation to Explain the Color of Blends Prepared from Precolored Fibers

A basic form of the Kubelka-Munk equation is proposed to explain the color be havior of blends of precolored fibers. For blends of fibers the textile industry commonly uses, which are not completely opaque, the color mixing mechanism consists of two independent processes acting simultaneously. According to the Kubelka-Munk theory for blended fibers as a translucent medium, among other parameters, the reflectance of each point on the surface is a function of the reflectances of the lower layers. This part of the color mixing mechanism is described by the law of subtractive color mixing that results from the multitude of colored dots formed by the different configurations of the fibers, from which their reflectances can be determined by the basic form of Kubelka-Munk theory. The number of these different colored dots is a function of the number of layers that are necessary to produce an opaque substrate. An increase in the fibers' translucency leads to an increase of the number of these colored dots. For fibers of the same diameter, the probability of the existence of points with a specific reflectance depends on the percentages of fibers in the blend. When this surface is viewed from a distance, the colored dots, like the dots on the screen of a color television set, mix spatially by averaging. Thus a combination of subtractive and partitive color mixing is taking place for blends.

Synthetic reflectance curves by subtractive colour mixing

An algorithm has been developed, using the subtractive primaries, that enables a ‘synthetic reflectance curve’ to be calculated for any set of XYZ values. A wide range of reflectance data for cyan, magenta and yellow primaries and white substrate can be used as data for the algorithm, provided the curves are smooth and correspond to those colours. These synthetic reflectance curves can be used as replacements for the data from measured physical standards for match prediction purposes. The synthetic standards have good colour constancy under a range of illuminants. They have been used to speed up the generation of fashion shade ranges selected initially on a CAD system.

Modeling pigmented materials for realistic image synthesis

This article discusses and applies the Kubelka-Munk theory of pigment mixing to computer graphics in order to facilitate improved image synthesis. The theories of additive and subtractive color mixing are discussed and are shown to be insufficient for pigmented materials. The Kubelka–Munk theory of pigment mixing is developed and the relevant equations are derived. Pigment mixing experiments are performed and the results are displayed on color television monitors. A paint program that uses Kubelka–Munk theory to mix real pigments is presented. Theories of color matching with pigments are extended to determine reflectances for use in realistic image synthesis.

Effect of Fiber Translucency on the Color of Blends of Precolored Fibers

Colored fibers can be blended together to create a spectrum of formulated yarn colors much like a paint formulator creates custom paint colors by blending dispersions of individual pigments. Unlike paint formulations, however, it is not possible to obtain a completely homogenized, uniform color with fibers because they remain separate entities on a macroscopic scale. When viewed under conditions that permit spatial or temporal integration of the discrete colors by the eye, one might expect the colors to combine much the way, for example, colored dots do on a television screen. This would require a simple weighted average or additive sort of color mixing mathematics, . but fiber blend colors follow much more closely the mathematics of subtractive color mixing, specifically the two-constant Kubelka-Munk theory. Simple experiments were performed to provide a better understanding of the color mixing mechanism operable in blends of differently colored fibers and a visual demonstration of that mechanism. The experiments show that both visual and spectrophotometric responses are linearly (additively) related to the component yarn colors in the blend only in the special cases of opaque component fibers or translucent fibers where there is no fiber overlap. For overlapping translucent fibers, the original component yarn colors form a mix according to the mathematics of the two-constant Kubelka-Munk theory, which is then additively integrated into the final blended yarn color. The two-constant Kubelka-Munk theory can be used over a wide range of fiber transparencies and degrees of overlap and can even approximate the color of opaque or non-overlapping fiber blends. Additive mixing mathematics, on the other hand, deviates rapidly from the actual visual or spectro photometric response as fiber translucency or overlap increases.

A quantitative demonstration of subtractive colour mixing

A quantitative demonstration of subtractive colour mixing

Instruction on Light and Color in Art at the Iowa State University

In the Applied Art Department at Iowa State University Ames, Iowa, U.S.A., we affirm the significance of light and its applications in art, architecture and interior design. As part of the program in our color classes, we attempt to clarify the processes of subtractive and additive color mixing and to study the effects of illumination of objects on the colors perceived. A useful demonstration for subtractive color mixing is the Balinkin-Dwight Filtergraph (Fig. 1) made by the Sargent-Welch Scientific Co., Skokie, Ill., U.S.A. It consists of a cabinet having interior walls painted white, an achromatic light source and a window that can accommodate single or superimposed pairs of plastic plates. Each plate shows a graph above and a single color filter below. The graph gives a wavelength composition of each color, its spectrophotometric curve. For an art student this is the critical step toward understanding that merely to name a color as it is perceived does not fully identify a filter. Figure 1 shows two superimposed plates. The single curve that starts at a wavelength of about 460 m/z and rises to a plateau corresponds to yellow-green. The entire area under that curve represents transmitted light when only that plate is present and the entire area above that curve represents absorbed light. The individual filters are first studied singly. For example, orange and amber can be perceived as being very close, however the curve for the amber filter shows that a relatively large amount of radiation in the red and violet is transmitted [1]. When two plates, representing different colors, are superimposed, as in Figure 1, the resulting mixed color appears in the central diamond shape with areas left for the two mixture parents at its sides. The resultant light transmission is represented by the area in which the two spectrophotometric curves overlap (e.g. the white area peaked at about 490 mp, in Figure 1). The mixed color perceived in the central area is of lower intensity than that of either of the unmixed colors perceived (to the right and left). This is expected because radiant energy is lost on passage through each filter. The Singerman Apparatus (Fig. 2), also made by the Sargent-Welch Scientific Co., is used to demonstrate additive color mixing. It consists of a cubical cabinet having interior walls painted mat black and a ground glass projection screen on one side. There are three clear incandescent lamps installed inside, whose emissions can be controlled independently from 'dim'