A feasible weave color scope inspection by using primary yarn colors to improve Jacquard reproduction quality

Producing a wide scope of weave colors is challenging in modern Jacquard weaving with limited weft color variety. The subtractive primary color yarns (cyan, magenta, yellow and black) are used to replicate varied Jacquard designs, but there is potential to improve the color reproduction quality by expanding a feasible weave color scope. Therefore, this research examined weave colors that are created by combining two sets of primary colors from different color systems. In color printing, six color pigments (i.e., cyan [C], magenta [M], yellow [Y], red [R], green [G] and blue [B]) are popularly used as primary colors for color reproduction. Therefore, weft yarn colors are selected in line with the six colors and a feasible weave color scope is inspected. The group of yarns is paired, and 225 weave color samples are produced to examine the color effects. The weave color samples are measured by a spectrophotometer and described by the CIELAB color space. The results show that the CIELAB color space was expanded by adding [R], [G] and [B] colored yarns. The hue and chroma ranges of the fabric samples were expanded compared with the fabrics produced by only [C], [M] and [Y] yarn colors. In this research, the possibilities in color reproduction are explored and the findings suggest great potential in producing a wide scope of weave colors by using primary yarn colors.

Weave colors are created by interweaving weft and warp yarn colors. 1,2 Weave structures also play an important role in producing various colors of woven fabrics, as the number of weft yarn colors is limited when applied to production. 3 Therefore, producing a large number of weave colors with a small variety of weft yarns is important in modern digital Jacquard weaving.
According to recent research from Kim et al., 4 6 -and its color gamut can display approximately 56% of the colors that are perceived by the human eye. 7 Thus, theoretically, there is a limited numbers of colors that are produced via mixing C, M, Y and K (black) pigments. In color printing, the four primary color pigments (CMYK) are widely used, but red [R], green [G] and blue [B] colors are also considered to enhance color reproduction quality. Therefore, this study aims to inspect the weave color effects when a pair of the two primary color sets is mixed. From previous research, it was discovered that [K] yarns only affect levels of chroma and lightness values. 4 Therefore, this research excludes the black color yarn and mainly focuses on six primary colors (i.e., [

C], [M], [Y], [R], [G] and [B]) to investigate hue changes.
Modern computer-aided design (CAD) systems provide a variety of design tools that are designed based on the standardized color database. 8-10 CAD systems offer varied methods for colorful Jacquard textile reproduction. 11,12 One of the significant design tools is a simulation that can provide a preview of woven fabric colors. However, due to the limited color database, it is difficult to simulate and display actual colors of woven fabrics on the screen. Therefore, color measurement has been important to describe colors quantitatively in the textile industry. One of the important color systems is the CIELAB system, which is based on colorimetry. [13][14][15] The International Commission on Illumination (CIE) introduced the L*, a* and b* chromaticity coordinates, which are now widely used to describe colors. 16,17 A representation of the CIELAB color space is shown in Figure 1(b). The L* values are the measure of lightness, which vary from 0 (black) to 100 (white). Positive a* values indicate the strength of the red component, while negative a* values correlate with the green sensation. Positive values of b* give measurements of yellowness and negative b* values indicate the strength of blue. 18 The L*C*h color space uses the same diagram as the L*a*b* color space, but it uses cylindrical coordinates instead of rectangular coordinates ( Figure 1). The hue angle (h) in the a*b* plane is a measure of hue, and the chroma is given the symbol C*. 19 Hue is the attribute of color sensation that is dependent on its dominant wavelength, and the hue angle (h) can be calculated by Equation (1). Chroma (C*) represents the colorfulness of an area judged as a proportion of the brightness of a similarly illuminated area that appears white. The value of chroma is expressed by Equation (2). 20 In this study, the weave color experiment results are described in CIELAB values This study aims to define a feasible weave scope if red, green and blue are added to Jacquard color reproduction and the details of weaving experiment results are introduced.

Materials and color measurements
The weft yarns used in this research are 100% multifilament polyester semi-dull color yarns, which was purchased from Able Shiny Co. The pantone printing colors are referenced to select the six yarn colors as close as possible to the primary colors (i.e., cyan  Figure 2. For fabrication, a Bonas Jacquard machine is used that is set with 150 denier off-white cotton yarns. The total ends of the warp are 3456 and 96 ends are placed per inch. As fine yarns are advantageous for natural color presentation, 22 50 denier yarns are applied to the weft and the weft density is set to 110 picks/inch. The six color yarns and 225 weave color samples are measured by a spectrophotometer (X-Rite Ci7500, UK) with Colour iControl software (X-Rite PANTONE V R , UK). The color coordinates of the samples were computed using the CIE standard observer (10 ) under a D65 light source. The measurement conditions applied to the yarn and weave color samples are diffuse/8 geometry and a 25 mm measurement spot. To measure the yarn colors, each color yarn was wound onto a yarn card with the highest possible uniformity manually. 23,24 To measure the weave color samples, fabrics were folded twice to provide fourlayered opaque samples. To reduce measurement variability that may result from fabric constructions and directionality of yarns, samples were repositioned and rotated to measure different areas of the fabrics. Each specimen was tested three times to determine the results.

Weave design and yarn color combinations
The compound weaves were designed based on sateen weave structures. The weft over warp interlacement point shows the color of the design and the Arahne Jacquard CAD system was used for creating digital weaving cards for the experiments. Fifteen color combinations are made with six yarn colors (i.e., ; the combination details are shown in Figure 3. The compound weaves were designed based on two sets of satin weaves (Table 1). Two yarn colors are chosen for the two weave designs. The weave structure applied to the first weft yarn is named "first weaves" and for the second weft color yarn, it is described as "second weaves." Table 1 shows the percentage of the weft over warp interlacement points. For samples 1-8, all the second weaves have 90% weft over warp points, while the first weaves of the weft over warp interlacements are progressively increased from 20% to 90%.
In contrast, from samples 9-15, the first weaves are fixed to 90%, while the weft over warp points for the second weaves are gradually decreased from 80% to 20%.
The weaving experiment is introduced in three groups. Figure 3 shows the details of the weaving experiments to examine the weave color results.

Results and discussion
Color spectra of yarns The six yarn colors are measured and the CIELAB results are shown in Figure 4.

Secondary weave color production using different primary colors
In this study, two sets of primary colors (CMY and BRY) are used for secondary weave color production. In the CMYK color system, a pair of [C], [M] and [Y] is juxtaposed to produce secondary colors (i.e.,   Table 1. The rest of the specimens were organized in the same order.     Table 1). The spectral reflectance curves of the [B] þ [C] samples are shown in Figure 6(a 0 ). The peak of sample 1 is at 470 nm, and it shifts to 460 nm from sample 2 to sample 4, and samples 5-15 have the highest peaks at 450 nm. All reflectance peaks are in the blue color zone. Figure 6(a 00 ) shows that the lightness decreased following the specimen numbers. The chroma of the weave samples is shown in Table 2.   Figure 6(b 0 )), which represents the red color. There is one high reflectance peak in the spectrum that indicates that the fabric samples have high chroma. 18 Table 2). The CIELAB values are shown in Figure 6 Figure 7(b). The first peak is at 500 nm (green), and the second peak is a broad peak ranging from 630 to 650 nm (red). Samples 1-3 mainly showed a 500 nm peak, but samples 4-7 showed two peaks that have similar intensity. Also, samples 8-12 had two peaks, but the peaks at the red range have a higher intensity. Samples 13-15 mainly showed the 630-650 nm peak. The reflectance spectral curves of the [M] þ [G] samples are shown in Figure 7(b 0 ). The first peak is at 480-490 nm (blue), and the second is a broad peak ranging from 620 to 650 nm (red). Samples 1-3 mainly show the first peak, but samples 4-13 showed both two peaks. Samples 14 and 15 mainly showed the peak that represents a red color.
Red and green are complementary colors, as shown in Table 3 1-8 mainly show the broadband from 620 to 700 nm, representing the red color. Samples 9-15 had a peak around 450 nm (blue), and the reflectance intensity also reached a peak at 700 nm, which results from the amount of red yarn colors shown on the surface. Images of the cyan and red yarn color combination are shown in Figure 7(c 0 ), and the wavelength versus reflectance curves of the [C] þ [R] samples are shown in Figure 7(d 0 ). The colors of the [C] þ [R] samples 1-9 mainly showed red tones with a broad peak ranging from 620 to 680 nm, while the peak gradually shifted to 480 nm for samples 9-15, which represents the blue color shown on the fabrics.    (Figure 8(b2)), which shows the higher chroma was created by juxtaposing the similar colors of the primary colors. As shown in Figure 8( yarn increases the lightness of the fabric samples. One of the more significant findings of this study is that the range of hue and chroma of the weave color samples is expanded by mixing a pair of two primary color sets. These findings contribute in several ways to our understanding of the possibilities in color reproduction and suggest great potential in producing a wide scope of weave colors by using primary colors.

Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding
The author(s) disclosed receipt of the following financial support for the research, authorship and/or publication of this article: This work was supported by the Arts and Humanities Research Council (project code AH/T006323/1), Loughborough University and the Hong Kong Polytechnic University.