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United States Department of Agriculture

Agricultural Research Service

Title: Measuring White Specks in Dyed Cotton Fabrics Using the Optimas Imaging System

Authors
item Bel, Patricia
item von Hoven, Terri

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 23, 2007
Publication Date: November 1, 2007
Citation: Bel, P., Von Hoven, T.M. 2007. Measuring White Specks in Dyed Cotton Fabrics Using the Optimas Imaging System. Journal of Cotton Science. 11:293–299.

Interpretive Summary: The white speck problem results in an estimated $200 million annual loss to the textile industry. Defined as undyeable clusters of undeveloped cotton fibers, white specks appear on the surface of dark dyed fabrics containing these undeveloped cotton fibers. Study of ways to avoid white specks requires a quantitative analysis for them but, to date, no such test was available. This report describes a system that consisted of a Microimage Video Systems color camera, an Imaging Technologies frame grabber, a personal computer, second monitor, Optimas software and a method to use Automatic thresholding to evaluate white specks via image analysis. The test is based on computerized analysis of a video image. Tungsten flood lighting yielded consistent, realistic images. Initially manual thresholding was used for each image, but by using lighting based on reflectance of the fabric, a uniform image is presented to the system and Automated thresholding can be used to minimize the operator's input. Based on studies of eight plain weave fabrics with extremely different levels of white specks, it was found that twenty'five three by four inch images give statistically significant data on the white speck problem.

Technical Abstract: White specks are fiber clusters that appear as small white flecks on dyed fabrics. Their minute size and depth of shade, increases the subjectivity and complexity. No standard methods exist to quantify the level of white specks. Image analysis was evaluated as a means to measure white specks in order to remove the subjectivity from the dye defect classification. This paper provides systematic procedures for the evaluation of white speck on dyed fabrics. Software, hardware and methods to obtain the white speck count, average size and percent white are discussed in detail. Optimas 5.2 software program utilizes a computer, two monitors, a video camera and a photographic camera stand. The study involved eight plain weave fabrics each with visually distinct levels of white speck content. These fabrics were initially used to identify the system, and software best suited for white speck quantification. The manual thresholding method was precise for one operator, but showed significant differences between operators. The fabrics were evaluated for their white speck content using the manual thresholding method (very operator dependent), and again using the new auto-thresholding method to minimize operator input. The auto-thresholding method used light meters to maintain constant lighting levels and then automatically sets the threshold levels. The system detected different levels of white specks for these fabrics as expected. The auto-thresholding method was much more accurate in actual count of white specks than the the manual method. This measurement system gives the textile industry a standard tool and procedure to measure fabric appearance.

Last Modified: 7/28/2014
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