## 2 Experimental Details  
### Fabric Sample Preparation  
Based on the designed yarn colors and weft-backed structures in the previous study [20], total forty-four blue-red mixed fabric samples were produced on LX 3202 Staubli Jacquard machine (Staubli, Sargans, Switzerland) for this experiment. Six different colors of red, green, blue, yellow, black, and white were selected for weft yarns, together with white warps and two weft-backed structures with and without middle regulating layers, were used for fabricating the fabric samples. Table 1 lists the detailed fabric specifications of the fabrics produced, and the fabric codes listed here are used in the following sections to express different fabrics.  
For the warp yarn, 100 denier (D) polyester filament yarns in white color (We) was applied while for the weft yarn, 75 D and 150 D polyester filament yarns in red (RE), green (GR), blue (BLU), yellow (YE), white (Wp), and black (BLK) were employed in the weaving trials. In order to enhance the color attributes of the fabric, a finer yarn of 75 D polyester filament was used in the fabric production. In addition, the effect of yarn count can also be investigated by comparing the fabric weaved by 150 D yarns with that produced by using 75 D yarns. The yarn color attributes were characterized by using a 7000A spectrophotometer (X-Rite, Incorporated, Grand Rapids, MI, USA). Table 2 lists the tested values of yarn color attributes. The weft-backed structure with the middle regulating layer consists of a face layer; a middle regulating layer, a back layer, and its corresponding weaves are illustrated in Tables 3 and 4 for blue-red color mixing and blue-red-black color mixing on the fabric face layer, respectively. The weft-backed structure without the middle regulating layer only has a face layer and back layer with detailed weaves for blue-red and blue-red-black color mixings on the fabric top layer shown in Tables 5 and 6, respectively. Moreover, by varying the mixed yarn color fraction through the weaves from weave M\({}_{\text{(BL+R)}}\) (1) to M\({}_{\text{(BL+R)}}\) (7), N\({}_{\text{(BL+R)}}\) (1) to N\({}_{\text{(BL+R+BK)}}\) (1) to M\({}_{\text{(BL+R+BK)}}\) (4), and N\({}_{\text{(BL+R+BK)}}\) (1) to N\({}_{\text{(BL+R+BK)}}\) (4), a series of blue-red and blue-red-black color-mixed colors were created on the surface of the fabric. The warp yarn density keeps constant for all fabric samples, which is 47 ends/cm, while the weft yarn density varies with the type of fabric. In order to reduce the negative effect of white warp floats at the fabric face on the color attributes of fabric, particularly on the lightness of the fabric, the function of cramming motion was implemented to lower the spacing between face weft yarns, which means that the weft density of the fabric can be increased. Cramming motion, also called regulator or retarding motion, means that the fabric take-up motion of designate picks is stopped, so that the part of fabric applying cramming motion contains more yarns per unit area [21]. The weft density is 120 picks/cm for the fabrics with and without regulating layer weaved by using 150 denier weft yarns. A lower fabric weft density of 120 picks/cm and a higher weft density of 160 picks/cm were also employed for producing the fabric with the regulating layer by using 75 D weft yarns to examine the effect of weft density on the fabric characteristics.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Fabric Sample**} & \multicolumn{2}{c}{**Yarn Count (Denier)**} & \multicolumn{2}{c}{**Yarn Color**} & \multicolumn{2}{c}{**Fabric Density (Threads/cm)**} \\ \cline{2-9}  & **Warp** & **Weff** & **Warp** & **Weff Yam Color Mixing** & **Warp** & **Weff** \\ \hline A (1–7) & 100 & 150 & White & Blue + Red & M\({}_{\text{(BL+R)}}\) (1–7) & 47 & 120 \\ B (1–7) & 100 & 150 & White & Blue + Red & N\({}_{\text{(BL+R)}}\) (1–7)