Reporting of Objective Color Measurements

Abstract

The analysis of color is frequently an important consideration when determining the efficacy of a variety of postharvest treatments.Consumers can easily be influenced by preconceived ideas of how a particular fruit or vegetable should appear, and marketers often attempt to improve upon what nature has painted.In spite of the significance of color in our work, however, many researchers continue to analyze this characteristic inappropriately.The confusion that results is unnecessary; easily computed and readily understood measures are available to clarify color descriptions for researchers and marketers alike.Specifically, many scientists in the field of market quality, who are using instruments such as the Hunter colorimeter (Hunter Assoc., Reston, Va.) and various Minolta chroma meters (Minolta, Ramsey, N.J.), analyze and publish a set of Cartesian coordinates generated directly by the instrument.These coordinates pinpoint the measured color in a three-dimensional color space.However, without further manipulation, this information does not provide an indication of hue and chroma-aspects of color that are intuitively understood by those in the marketing chain from producer to consumer.These aspects of color are addressed directly in the color chart-based Munsell notation that specifies the elements of perceived color as value (lightness, from black to white on a scale of 0 to 10), chroma (degree of departure from gray toward pure chromatic color), and hue (red, orange, yellow, green, etc.).In contrast, the instrumentally obtained coordinates, CIE 1931 (Y, x, y) or CIE 1976 (L*, a*, b*), provide information on lightness directly but require some computation to yield explicit measures of chroma and hue (Hunter and Harold, 1987).CIE refers to the Commission Internationale de l'Eclairage (International Commission on Illumination).In the CIE 1976 (L*, a*, b*) color space, abbreviated CIELAB, the lightness coefficient, L*, ranges from black = 0 to white