关键词: 异形网点, 提花织物, 灰度仿真, 织物图像, 明度差, 分区比较

Abstract:

Objective Aiming at the situation that the dot shapes applied to the grayscale simulation jacquard fabric are limited to simple geometry, a special-shaped dot database design method was proposed, and the reproduction performances of the created special-shaped dot databases in the design of jacquard fabric were compared and investigated, attempting to provide a new method for promoting the color simulation of jacquard fabric design technology.

Method Four specially-shaped dot databases were designed by graphic generation technology. One group of fabric color cards showing grayscale from black to white gradient changed and four jacquard fabric samples representing an image were woven by applying the special-shape dot databases. All fabric samples were interwoven from one set of white warp and black weft yarns. The materials of warp and weft threads were both 23.3 dtex×2 silk, and the warp and weft filling density were both 1 100 threads/(10 cm). By comparatively analyzing the average lightness differences between the values of the fabric color cards and the original grayscale color, and between the value of the jacquard fabric samples and that of the original image, the grayscale simulation feature of the special-shape dot databases in the color simulation design of jacquard fabric were explained.

Results The mean value of the fabric color cards woven using the tree-shaped dot database and the original grayscale from the black to the white were calculated, respectively, and the difference between them was only 1, which indicated that the grayscale simulation performance of the tree-shaped dot database was excellent compared with the another six group of fabric color cards applying frequently-used shaded weave databases in total (Tab. 1). In order to further analyze the color simulation capability of the special-shape dot databases for rending complex image, six jacquard fabric samples were produced by using the four special-shape dot databases and two shaded weave databases, respectively. All figured jacquard fabric samples are scanned to become digital images, and then each digital jacquard fabric image was divided into nine pieces one by one (Fig. 4). The average lightness values of the nine pieces in one fabric image were calculated in sequence (Fig. 6), and the average lightness differences between the each fabric image pieces with that of the original image pieces were counted accordingly (Tab. 3). From the data of the six groups and their average lightness differences with the original image, it was shown that the four jacquard fabrics using special-shape dot databases had slight deviation value in grayscale simulation performance, but the average value difference between the two groups of jacquard fabrics with shaded weave databases was obvious. In addition, the heart-shape dot database had the best performance among the four special-shape dot databases, the ingot-shape was the second, the third was the tree-shape and the last was the leaf-shape. In view of the comparative analysis of the average lightness difference between the jacquard fabric images expressed by special-shape dot databases and by shaded weave databases, it was proved that the special-shaped dot databases have better and more stable grayscale simulation performances than that of the shaded weave databases that are widely used for the design of the color simulation jacquard fabrics in present.

Conclusion Special-shape dot structure fabrics have more stable grayscale simulation performance than the shaded weave structure fabrics, and the fullness of the dot shape is found to be the main factor affecting the grayscale simulation effect in the experiment. The design and application of the special-shaped dot database, on the one hand, is a breakthrough in the conventional dot shape and develops new design paths to the production of color simulation jacquard fabrics with graphic generation technology. The application research of special-shaped dot database in grayscale simulation of jacquard fabrics provides a new idea and design references for the development of creative jacquard fabrics.

Key words: special-shape dot, jacquard fabric, grayscale simulation, fabric image, lightness difference, partition comparison