Visually Perceived Attributes of the Appearance of Materials and ASTM Progress Toward Their Measurement

Abstract

To analyze appearance attributes optically, one first separates the chromatic attributes from the geometric ones. The chromatic, or color, attributes may be represented in a variety of forms which start with the purely physical spectrophotometric curves. By incorporating the sensory processes of the human observer, one converts spectrophotometric data to colorimetric specification by use of the CIE Standard Observer and Coordinate System. To obtain analyses which relate closely to the observer's sensory impressions, one can convert CIE specifications to one of several opponent-colors (L,a,b-type) analyses or to hue, value, and chroma of the Munsell-type analyses. These sensory-related color specification systems can be used to locate points representing colors in three-dimensional coordinate systems. Geometric attributes are those related to the geometric manners in which objects and materials distribute light and are known by terms such as gloss, turbidity, texture, and the like. Measurement methods for many of the various geometric attributes have been developed. Total instrumental analyses of the physical correlates of appearance are so complex that measurement is not feasible and is never attempted. There do exist, however, a large number of practical, useful methods for instrumentally measuring specific attributes of the appearance of materials. Many of these have been standardized in print by the American Society for Testing and Materials (ASTM), which now has the largest published collection of appearance analyses in existence. Although ASTM has accomplished much in promoting measurements of appearance attributes, there exist important requirements for test procedures not yet prepared. The technical state of the art has recently progressed so that ASTM should now be able to meet these unsatisfied requirements.

Peel Gloss as a Potential Indicator of Banana Ripeness

“…It can be seen that a good correlation was found between gloss and some of the other parameters measured. It is well known that gloss measurements made at high coincident angles, such as 85°, are most suited for matt surfaces and low coincident angles are most suited for high gloss surfaces (1). When the coincident angle for gloss measurement was 85°, high and significant correlation coefficients (P < 0.01) were found with seven of the measured chemical and physical parameters.…”

“…Gloss is a perceptual attribute of surfaces related to the degree to which it simulates a perfect mirror in its capacity to reflect incident light (1), and its commercial importance in the food industry is well known. For instance, the consumer will always prefer apples and cucumbers with a shiny appearance and mushrooms and green beans with a dull appearance (2).…”

Gloss Properties and Surface Morphology Relationships of Fruits

“…This is indicated by the fact that shaded plants and tissues rarely possess such superficial characters (Barber and Jackson, 1957). Since gloss is a function of the inherent reflectivity of a surface and its specular and diffuse reflectances (Hunter, 1952;Skilling, 1948), epicuticular wax would be partially responsible for gloss properties of plant tissues. Such properties are of particular importance in the fruit and vegetable trade.…”

Nondestructive Measurement of Peel Gloss and Roughness to Determine Tomato Fruit Ripening and Chilling Injury

“…It is well known that high coincident angles are more suitable for matt surfaces (Hunter, 1952) Thus we assumed that for a slightly glossy surface such as tomato peel an inbetween angle (60Њ) would be more suitable.…”