|Knowlton, James - USDA-AMS|
Submitted to: American Association of Textile Chemists and Colorists Abstracts
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 15, 2008
Publication Date: November 1, 2008
Citation: Thibodeaux, D.P., Rodgers, J.,Campbell, J., Knowlton, J. 2008. THE FEASIBILITY OF RELATING HVI COLOR MEASUREMENTS TO CIELAB COORDINATES. American Association of Textile Chemists and Colorists Abstracts (AATCC Review). 8(11):44-48. Interpretive Summary: With the demise of the U. S. textile industry, U. S. cotton producers must increase their efforts for global marketing of their fiber. Since U. S. cotton is marketed based on high volume instrumentation (HVI), our global customers are beginning to question the basis of some of the HVI instruments. One of these is the measurement of cotton color (HVI uses the cotton colorimeter to measure reflectance (Rd) and yellowness (+b). It has not as yet been demonstrated to the international community that HVI color is related to a more universally recognized color measurement system such as the CIE L*a*b* (CIELAB). CIE is short for Commission Internationale de l'Eclairage which is the French title of the international commission on light. In the modern three-dimensional color model L* represents the degree of lightness of color, a* determines the degree of color ranging between magenta and green, and b* determines the degree of color ranging between blue and yellow. The objective of the present work is to demonstrate the feasibility of relating HVI color measurements to a laboratory instrument yielding measurements in the CIELAB system. The approach was to obtain a total of ten reference tiles and twelve reference cottons that have been measured for Rd and +b on the master cotton colorimeter of the USDA-AMS-Cotton Program in Memphis, Tennessee. These same objects were then measured on a GretagMacbeth laboratory spectrophotometer calibrated to the CIELAB color system. Relationships between the HVI (Rd,+b) and the CIELAB (L*, b*) were examined and are reported herein. In Figure 1 the relationship between Rd and L* for calibration tiles and cottons measured on the HVI Master Colorimeter and the GretagMacbeth laboratory spectrophotometer. Very good correlations were found between the standard CIE color parameters (L*, b*) and the master colorimeter's (Rd, +b), respectively. As a result of this preliminary study we can conclude that it would be feasible to relate the HVI color measurements to a modern color measurement system.
Technical Abstract: We have begun work to demonstrate that HVI color measurements can be related to measurements made on a laboratory spectrophotometer set for measurement in the CIE L*a*b* (CIELAB) color space. The color of cotton as measured by HVI is characterized by two parameters: brightness or reflectance (Rd) and yellowness (+b). Standard color tiles and calibration cottons representing a wide range of Rd and +b values were measured on the AMS Cotton Program's master colorimeter. They were then measured on a GretagMacbeth laboratory spectrophotometer. Allowing for differences in slope and offset, very good correlations were found between the standard CIE color parameters (L*b*) and the master colorimeter's (Rd, +b), respectively.