Location: Cotton Structure and Quality Research
Title: UPDATING HVI COLOR MEASUREMENTS Authors
Submitted to: Proceedings of Engineering Fiber Systems Conference
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2005
Publication Date: June 1, 2006
Citation: Rodgers Iii, J.E., Thibodeaux, D.P. 2006. Updating hvi color measurements. Proceedings of Engineering Fiber Systems Conference. p. 50. Technical Abstract: The “grading” of U.S. cotton has been based on the Uster High Volume Instrumentation (HVI) instrument for several years. A key quality measurement of the HVI unit is cotton color. Using a camera-based system and two broad-band filters (two “wavelengths”), the quality parameters of Rd (diffuse reflectance) and +b (yellowness) are obtained with the current HVI units. The standards used for the HVI units are based on AMS reference tiles and cottons, not on scientifically recognized standards such as those from NIST (National Institute of Standards and Technology). The color of the ceramic and cotton batt standards are measured on a master colorimeter-HVI by AMS. Two areas of significant opportunities and challenges for updating and improving the rapid and precise measurement of cotton color are 1)a better understanding and application of the present color system (Rd- +b) to well-known color systems (e.g., L*a*b*) and 2)the development of verifiable or “traceable” cotton color standards from AMS. In that light, new procedures and color systems are being investigated to update and improve the present color measurements and AMS color standards protocols. A multi-team program was implemented to study the relationship between HVI Rd- – +b and L*a*b*, to determine “standard” L*a*b* values for AMS standards, to determine the feasibility of verifiable AMS color standards, and to determine the primary physical/procedural sources of variability for the AMS standards. Initial results on one full range color spectrophotometer yielded very good correlations between the standard CIE color parameters and the HVI master colorimeter’s color parameters (L*-Rd, b*-+b). Not unexpectedly, L* is normally higher than Rd, while very good agreement is often observed between b* and +b. These encouraging initial results offer great promise and potential for traceable HVI color measurements to a laboratory spectrophotometer calibrated to the CIELAB color system with a NIST-traceable standard The sample measurement protocols have been extended to ten different color units (portables and bench-top) from five color instrumentation vendors.