画像解析による天然染料と合成染料で染めた綿染色布の色彩の違い

摘要

Image analysis was applied to evaluate the colors of cotton fabrics dyed with natural and synthetic dyes. Color measurements of these fabrics were done with a commercially available color scanner and a colorimeter. The X, Y, Z, L*, a* and b* values of the CIE color system were obtained for each pixel (i,j) in the image by respective measurements and by appropriate transformation of the values. The colors of the fabrics were measured either vertically or horizontally with a scanner having 512 divisions for every 6.5 cm, with ca. 0. lmm spacing. Total values of L*, a* and b* for all pixels in the vertical direction for pixel position (i) in the horizontal direction (i=0~511) were SVi-L*, SVi-a*, and SVi-b*, respectively. Similarly, SHj-L*, SHj-a*, and SHj-b* were also obtained for all pixels in the horizontal direction for pixel position (j ) in the vertical direction (j=0~511). The SVi-L* and SHj-L* values of fabrics dyed with natural dyes showed large degrees of variation, while those with synthetic dyes showed very small degrees of variation. The difference between the colors of the cotton fabrics dyed with natural and synthetic dyes were discussed in relation to the coefficient of variation.%天然染料による染色は，染色方法は極めて複雑であり，経験と熟練を積まないと良好な染色を行うことは難しい．しかし，美術的あるいは工芸的分野においては，この技法が根強い伝統として継承されている．天然染料は合成染料とは染色性の点で大きく異なっている1）．ほとんどの天然染料は媒染されるが，合成染料は繊維の中まで拡散し，繊 経に固着される．