were transformed into chroma ( C *) and hue angle ( h °) using the equations: C* = (a* 2 + B* 2 ) 1/2 and h ° = tan −1 (b*/a*) ( McGuire, 1992 ). Richness of color is represented by C* and h° represents the dominant color wavelength where 0° = red
Patrick J. Conner and Dan MacLean
Ruixiang Yan, Joshua B. Gurtler, James P. Mattheis, and Xuetong Fan
with Hunter UltraScan VIS colorimeter (Hunter Associates Laboratory, Reston, VA) using a 1.3-cm measuring aperture. D65/10° was used as the illuminant-viewing geometry. Hue and chroma were calculated from a* and b* values ( McGuire, 1992 ). ORAC assay
Yiguang Wang, Chao Zhang, Bin Dong, Yaohui Huang, Zhiyi Bao, and Hongbo Zhao
on CIE L*a*b* of fruit peels ( L* = lightness, a* and b* = chromatic components, C* = chroma, and h o = hue angle). The sample numbers correspond to those in Table 1 . Fig. 2. Fruit of chinese flame tree from different color groups. The
Wilfredo Seda-Martínez, Linda Wessel-Beaver, Angela Linares-Ramírez, and Jose Carlos V. Rodrigues
was dried in an oven at 65 °C. Hue angle and chroma were calculated from a* and b* using formulas from McGuire (1992) . Percentage dry matter was calculated as dry weight divided by the fresh weight and multiplied by 100. Statistical analyses. Symptom
Peter Alem, Paul A. Thomas, and Marc W. van Iersel
-expanded, uppermost bracts were sampled from each plant and their size determined using a leaf area meter (LI-3100, LI-COR, Lincoln, NE). In addition, bract chroma (a measure of color intensity) was measured using a colorimeter (XL-20; Gardner Instruments Laboratory
Mohamed S. Al-Saikhan, Luke R. Howard, and J. Creighton Miller Jr.
The influence of variety and location on flesh color was examined using Texas and Colorado grown tubers from ten yellow flesh and two white flesh potato varieties. Flesh color was determined using a Hunter Colorimeter, which gives three readings, L* (lightness to darkness), a* (green-red index) and b* (blue-yellow index) Three readings were taken from each tuber at the distal end, center, and stem end. There were significant differences in color among varieties grown in each location for L*, and at both locations, the center was darker. The distal end had the highest chroma and hue angle values at both location. Significant differences were found between the same variety grown in both locations for L*, chroma, and hue. Chroma and hue were greater in Texas grow tubers which indicated more redness. Lower mean hue angle values indicated that Texas tubers were more red, whereas Colorado tubers were yellow. Higher mean chroma values indicated that Texas grown tubers were redder than Colorado grown tubers. L*, chroma, and hue angle are the most useful quantitative measurements.
Peter J. Landschoot and Charles F. Mancino
This study was conducted to determine: 1) if the Minolta CR-310 Chroma Meter can detect color differences among bentgrass (Agrostis stolonifera L., A. capillaris L.) cultivars maintained as a turf; 2) how the CR-310 parameters of hue angle, lightness, and chroma compare with visual color assessments; and 3) if the CR-310 can provide consistent color measurements among evaluators. Differences were detected among cultivars with respect to hue angle, lightness, and chroma. Hue angle and chroma were significantly correlated with visual color assessments when data were averaged across all evaluators. Lightness was not strongly associated with visual color assessment. Differences were found among evaluators for visual color assessment, lightness, and chroma, but not for hue angle measurements. Thus, hue angle appears to be the most consistent CR-310 parameter for measuring color of bentgrass turf. These results indicate that the CR-310 can be used to evaluate the color of bentgrass cultivars maintained as a turf and provides consistent hue angle measurements among evaluators, regardless of experience in rating turf color. The CR-310 is probably best used for measuring relative color differences and may be useful if cultivars of similar color are desired in blended turfs.
Tommy E. Thompson, L.J. Grauke, and E.F. Young Jr.
The Munsell Color System was used to study pecan [Carya illinoinensis (Wangenh.) K. Koch] kernel colors and color changes for 21 clones, 11 locations, and five storage methods for nuts collected over 4 years. Hue readings ranged from 10.0 (10 red) to 22.5 (2.5 yellow). Value readings ranged from 2.0 to 8.0, and chroma readings ranged from 1.0 to 8.0. A total of 91 classes (individual combinations of hue, value, and chroma) were needed to describe all kernel colors. Overall, one class 115.0/5/4 (hue/value/chroma)] accounted for 3979 of the 32,078 readings taken, and the 15 most common classes accounted for 80.7% of all the readings. This system of color determination was well-suited for pecan color determinations and continues to be used routinely as a part of our breeding and genetics program to define this important quality trait in pecan.
W. Garrett Owen and Roberto G. Lopez
* values [ratio between blueness and yellowness (blue: b* = −60; yellow: a* = +60)] were determined and used to calculate chroma (C*) and hue angle ( h °). Chroma is a measure of saturation and was calculated as On a circular scale, h °, or tone, indicates
Eleni Tsantili, Miltiadis V. Christopoulos, Constantinos A. Pontikis, Pantousis Kaltsikes, Chariklia Kallianou, and Michalis Komaitis
presented in Newtons (N). Color was measured by a chromatometer (CR-300; Minolta, Ahrensburg, Germany) and was expressed in L*, hue angle (h o ), and chroma (C*). Three color measurements were made on each unpeeled fruit, two on opposite sides and one on the