MODERN COLOR MEASUREMENTS for COTTON— FUNDAMENTALS and ISSUES

Authors: Rodgers Iii, James; Thibodeaux, Devron; Campbell, Jacqueline

Submitted to: Engineered Fiber Selection Conference
Publication Type: Proceedings
Publication Acceptance Date: 3/1/2006
Publication Date: 6/1/2006
Citation: Rodgers Iii, J.E., Thibodeaux, D.P., Campbell, J.H. 2006. Modern color measurements for cotton— fundamentals and issues . Engineered Fiber Selection Conference.

Interpretive Summary: Color measurements of cotton fiber and cotton textile products are key and critical quality and process measurements. Color measurements for the classing of U.S. cotton have been performed on the Uster High Volume Instrumentation (HVI) instrument for several years. Color measurements of cotton textile products (yarns, fabrics, etc.), as well as the color of cotton fiber, has been performed by colorimeters and color spectrophotometers for decades. Before we can analyze and interpret the results of these color measurements, we need to understand how color is perceived and measured. Human color perception results from the interaction of three components—a light source, an object, and a detector (the eye and brain). Color measurements are the processes whereby human color perception can be measured and described with a color instrument. Color measurements of a solid involve the combination of the reflected light spectrums of an illuminant (light source), an object, and the use of color matching mathematical functions to yield a 3-dimenisonal color coordinate system, designated as the tristimulus color values X, Y, and Z. From XYZ, several well-known color systems can be derived to describe the color of an object, including L*a*b*. Several questions must be asked and answered prior to making color measurements—what type of instrument to use, instrument geometry, instrument settings/conditions, and sample specifics. The impact on color results and measurements from these instrumental and sample differences can be significant. Specific examples of sampling and instrumental variables that could impact color measurements are given.

Technical Abstract: Color measurements of cotton fiber and cotton textile products are key and critical quality and process measurements. Color measurements for the classing of U.S. cotton have been performed on the Uster High Volume Instrumentation (HVI) instrument for several years. Color measurements of cotton textile products (yarns, fabrics, etc.), as well as the color of cotton fiber, has been performed by colorimeters and color spectrophotometers for decades. Before we can analyze and interpret the results of these color measurements, we need to understand how color is perceived and measured. Human color perception results from the interaction of three components—a light source, an object, and a detector (the eye and brain). Color measurements are the processes whereby human color perception can be measured, quantified, and described with a color instrument. Color measurements of a solid involve the interaction and mathematical spectral combination of an illuminant, the object’s reflectance, and the use of color matching functions to yield the tristimulus color values X, Y and Z. From XYZ, several well-known color systems can be derived to describe the color of an object, including L*a*b*. Several questions must be asked and answered prior to making color measurements—what type of instrument to use, instrument geometry, instrument settings/conditions, and sample specifics. The impact on color results and measurements from these instrumental and sample differences can be significant. Specific examples of sampling and instrumental variables that could impact color measurements are given.