ARS | Publication request: IMAGE-PROCESSING SOLUTION TO COTTON COLOR MEASUREMENT PROBLEMS PART II INSTRUMENT TEST AND EVALUATION

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 1, 2004
Publication Date: N/A

Interpretive Summary: Measuring color in cotton samples is the most important aspect of determining prices in cotton. It can also be important in determining how rigorously cotton should be processed during ginning. A good-color cotton could command a high price, and so rigorous processing to reduce the amount of foreign matter in the cotton may be warranted, as it could improve the price of a unit mass of cotton. However, an off-color cotton would be associated with a lower price, possibly regardless of the level of foreign matter in it. Thus, in the latter case rigorous processing may not be warranted, as it would tend to reduce the overall amount of cotton available for sale without raising the price appreciably. Therefore, accurate measurement of cotton color is very important. Furthermore, particles of foreign matter affect the measured color when diffuse-reflectance color-measurement techniques are used. So it is important to develop new methods of cotton color measurement that neglect the affect of foreign matter on color. To this end, an instrument was developed to use image analysis of cotton samples in order to neglect image portions associated with foreign matter particles, thus allowing the color measurement to be made on the basis of fiber color alone. This experimental cotton color/trash meter was described in detail in a separate manuscript. As reported in this manuscript, the experimental meter was tested extensively on a large number of cotton samples varying widely in color and trash content. Results of detailed statistical analyses indicated that the experimental meter was as accurate at cotton color measurement as were conventional meters, and that measurements with the experimental meter were better for estimating true fiber color when. The experimental meter would thus be a good substitute for conventional meters in situations where a significant amount of foreign matter is present in the cotton fiber, such as during gin processing.

Technical Abstract: An experimental cotton color/trash meter was developed previously for the purpose of improving cotton color measurement by removing trash-particle effects on color measurement with image processing. In this work, the experimental meter was tested extensively on a large number of cotton samples varying widely in color and trash content. Testing involved (1) comparing the measurement accuracy of the experimental meter to that of conventional meters that use diffuse reflectance for color measurement, and (2) comparing the experimental and conventional meters' ability to predict clean lint color from that of uncleaned lint. Results indicated that basic cotton color measurement was as accurate with the experimental meter as it was with conventional meters. Additionally, the experimental meter's color measurements on uncleaned lint correlated better with cleaned lint color than did those of the conventional meters in every case. With the Z (blue-band reflectance) color measurement, the superiority of the experimental meter's correlation between uncleaned and cleaned lint color was statistically significant. The reduction in root-mean-square error with the experimental meter was about 14% for the Y (broad-band green reflectance) measurement, and about 22% for Z. These reductions in prediction error had statistical as well as practical significance.