HVI color and UV/visible spectral response of cotton fibers

Authors: Liu, Yongliang; Gamble, Gary; Thibodeaux, Devron

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/11/2010
Publication Date: 4/21/2010
Citation: Liu, Y., Gamble, G.R., Thibodeaux, D.P. 2010. HVI color and UV/visible spectral response of cotton fibers. National Cotton Council Beltwide Cotton Conference, January 4-7, 2010, New Orleans, LA. p. 1431-1435.

Interpretive Summary: To ensure a fair trade and good-quality textile products to the consumers, USDA’s AMS has established the official color standards for grading cottons. Experienced classers visually compare the cotton fiber with the color standards and then assign a color grade. Clearly, the classification process is both labor intensive and prone to both human error and classer-to-classer variations. Hence, USDA has updated the cotton classing method with the use of HVI system, in which two unique color parameters (Rd, lightness, and +b, yellowness) were produced and color grade was determined from the Rd ~ +b diagram. There has been substantial inconsistence between classers and HVI, partly due to classer’s subjective perception and partly due to HVI’s 2-filter limitation. To improve the agreement, several researchers have suggested various approaches, including the consideration of +a (redness) factor, the scanning of large cotton surface, and the application of innovative data analysis. From a different view, this work introduced relative yellowness (%+b) or relative lightness (%Rd) that were derived from HVI Rd and +b readings. In order to examine the effectiveness of %+b or %Rd and also its equivalency to that of +b or Rd, cotton physical properties and the UV/visible spectra were utilized. The results indicated the remarkable improvement for describing the cotton lightness with the use of %Rd. This outcome provides regulators and also cotton fiber / fabric / textile researchers a new sight in the grading and classification of cotton color.

Technical Abstract: Classification of cotton color is assessed by both human classers and HVI measurements. However, there are demonstrated inconsistencies between them, partly due to the human classer’s subjective perception and partly due to HVI’s 2-filter limitation. To improve the agreement, a number of attempts have been made, including the consideration of +a (redness) factor, the scanning of a larger cotton surface, and the adoption of neural network classifiers. As a different approach, this work introduced relative yellowness (%+b) or relative lightness (%Rd) that were derived from HVI color Rd and +b readings, and explored the feasibility of one variable for the characterization of cotton color. In order to examine the effectiveness of %+b or %Rd and also its equivalency to that of +b or Rd, cotton physical properties and UV/visible spectra were utilized. The pair of %+b and +b had a more pronounced relationship than that of %Rd and Rd, and the first PC (PC1) scores revealed more remarkable correlation with %Rd than with Rd. Furthermore, the PLS model performance was significantly improved for cotton lightness description with the use of %Rd.