Colorimetric and Spectral Properties of Natural Colorants Used in Handmade Traditional Persian Carpets

The colorimetric specifications and the dimensional properties of the spectral reflectance of natural dyes, which are used in the traditional handmade Persian carpet, are investigated. Different natural dyes are employed on woolen yarns to provide a collection of 286 colored samples. The colorimetric expansion and the spectral behaviors of samples are compared with Munsell color-matt finish collection. The principal component analysis technique as well as the non-negative matrix factorization method is employed for the spectral evaluation of datasets. Although the natural dyes present smaller color gamut in comparison to the Munsell dataset, the dimensional properties of the reflectance spectra of both datasets provide very close cumulative percentage of variances. The results are reconfirmed by the calculation of the mean root square errors between the original and the reconstructed spectra of samples from reduced spaces employing different numbers of positive-negative and all positive bases as well as the CIELAB color difference values under D65 and A illuminants and 1964 standard observer.