## 3 Results and Discussion  
### Color Analysis Based on HSV Space  
Three primary colors and nine secondary colors were extracted through the above clustering approach, and the results are shown in Table 2. As for the HSV analysis, the three primary colors were red and purple tones, separately named with numbers and uppercase letters, and the nine secondary colors were red, yellow, purple, and cyan tones, named with numbers and lowercase letters. Though the secondary clustering method of the primary color, the representative color of the brocade samples shows a large area of red-yellow color.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Representative Colors** & **Proportional Color Cards** & **Name** \\ \hline primary colors & & 1A, 2B, 3C \\ secondary colors & & 1a, 2b, 3c, 4d, 5e, 6f, 7g, 8h, 9i \\ \hline \hline \end{tabular}
\end{table}
Table 2: Cluster analysis of the primary and secondary colors.  
Figure 6: Principle of the Apriori algorithm.  
In visual perception, the color tone is determined by the differences in color brightness and saturation. The Practical Color Coordinate System (PCCS) was developed by the Japan Color Research Institute in 1964 and is based on psychological elements. Since the main feature of the PCCS is its hue-tone system, the PCCS has the advantage of treating color as an image using its tone. The Practical Color Coordinate System (PCCS) is commonly used by designers to achieve various color matching relationships, and the principle is different tone series [25]. The 12-tone distribution and the corresponding color representation are shown in Figure 6(a).  
Therefore, the tone distribution of the representative colors for the brocade samples was analyzed using the PCCS. The brightness and saturation within the color system are closely correlated with the S and V channel scales in HSV space, which can be used to identify various tones by specific values. The values of the S and V channels were divided evenly, and the color tones and the percentages were calculated to compared with the system. In Figure 6(b), the result shows that the brocade pattern colors are primarily concentrated in five tones. The main colors are light and soft colors, accounting, respectively, for 27.65% and 20.35%. Grayish, light grayish, and pale are next, accounting for 39.48% of the total. In addition, dark grayish and dull only constitute 8.35%. The other colors, particularly the deep, vivid, or other colors with strong color preferences, merely account for approximately 1% of the total color distribution.  
The analysis results showed that the majority of these fabrics have a red-yellow basis, with an overall color scheme consisting of light or soft tones. This indicates that the textiles from the fourth through eighth centuries were generally produced in a rustic manner. According to Chinese theory of Yin and Yang, yellow is associated with earth and was considered the most natural color according to the old \"Five-Element theory\" [26]. Both red and yellow have been historically revered, as yellow was frequently linked to the monarchy and red symbolized joy. In addition to the light and soft tones with a large proportion in the whole color scheme, the grayish and light grayish tones account for approximately 30% to make the bright colored fabrics exhibit a natural appearance.