非规则网点库设计及其织物灰度色阶呈色性能与评价

Design of an irregular dot database and coloring performance and assessment of fabric grayscale

针对缎纹影光组织对均匀过渡的黑白渐变色呈现不稳定的问题,文章提出一种非规则几何网点库设计方法,并比较分析了采用该网点库的织物色卡呈色性能。通过将2组不同尺寸的非规则网点库和2组不同加强方向的缎纹影光组织库,应用于黑白渐变色阶和灰度图像,设计织造了4组色卡织物和4幅提花织物样品。在分别考察了4组色卡织物测色数据与原渐变色阶之间明度差的基础上,进一步分析了两者之间的结构相似性,结果表明:2组非规则网点色卡织物相对于2组影光组织色卡织物,与黑白渐变色阶之间的明度差均值降低了10.2%;在色阶标准差上,前者较后者下降了38.8%;在结构相似性(Structural Similarity,SSIM)方面,前者的SSIM均值较后者的提高了52.9%,3项评价指标均表明非规则网点织物具有更好的灰度仿真表现。4幅提花织物样品的灰度仿真效果直观展示了上述研究结果。

Fabrics from traditional hand-designed photographic ones to modern digital jacquard ones are characterized by the design and combination of shaded weave,but the shaded weave in the expression of gray colors will produce color bias,which can not meet the requirements of color stability of simulation fabrics.In this study,we proposed a principle and method of designing a graphic database with irregular dot structure and explored its color rendering law for the problem of inaccurate color expression when the shaded weave was applied to black and white simulated jacquard fabrics.In this paper,on the basis of exploring the difference in brightness between the color measurement data of the four weave samples and the original gradient color scale,we further analyzed the structural similarity between the two,compared the simulation performance of irregular dots and shaded weave swatch fabrics from the three levels of brightness,contrast and texture structure,and investigated the color scale rendering of irregular dots in all aspects.Finally,we investigated the simulation effect of irregular dots and shaded weave on jacquard fabrics through design practice.The analysis results of the color card fabric samples show that the irregular dot color card fabrics are closer to the black and white gradient in the overall brightness simulation performance than the shaded weave,and have better color uniformity in the color scale performance.The irregular dot is more ideal than the shaded weave in color card gradient,especially in the high brightness area closer to the black and white gradient.The average value of lightness difference between the two groups of irregular dot color card fabrics and black and white gradient color scale is reduced by 10.20%compared with the two groups of shaded weave color card fabrics;the standard deviation of color scale of the former decreases by 38.80%compared with the latter,indicating that the former has better color uniformity;the area difference between the lightness curve of the irregular dot color card fabrics and the ideal lightness color scale is smaller,indicating that the former has better color accuracy in simulation.In the evaluation of fabric structure similarity,the 183 type irregular dot color card fabric is closest to black and white gradient color scale in the overall trend,and the simulation performance of the 122 type and the 183 type irregular dot fabrics is close to it.In the evaluation of structural similarity,the mean SSIM value of the irregular dot fabric group is 52.90%higher than that of the shaded weave fabric group,indicating that the irregular dot fabrics have better simulation performance.The simulation performance of the two sizes of irregular dot fabric is closer,indicating that its color simulation ability has good stability.The objective analysis of the two kinds of color card fabrics shows that the irregular dot in simulation performance is better than the shaded weave,and the simulation performance is better with the increase of dot.In terms of fabric simulation evaluation,the structure similarity evaluation can synthesize a variety of influencing factors of fabric simulation,and is more scientific and intuitive than the comparative analysis of brightness value,which can provide an effective evaluation method for fabric simulation.The final design practice shows that the irregular dot can have better application effect than shaded weave on black and white simulated jacquard fabrics,and can meet the expected color rendering requirements of simulated jacquard fabrics.Specifically,the dot sense of the 122 type irregular dot jacquard fabric is weaker than that of the 183 type,and is more in line with the requirements of human eyes for simulated jacquard fabrics.The irregular dot construction based on the hybrid screening technology has unique arrangement and irregular dot shapes,and its application to the simulated jacquard fabric has a better simulation effect than the shaded weave.The innovative design of an irregular dot database is another supplement to the existing technology of black and white simulation jacquard fabrics,providing a new method to further optimize the color rendering of simulation fabrics and providing design reference for color simulation jacquard fabrics.