Image Analysis Measurements of White Specks on U.S. Extreme Varieties of Cotton

Abstract

White specks are a specific type of fiber defect that result in high financial losses to the cotton industry. Fiber entanglements are called neps. Neps that involve immature fibers do not dye properly and appear as white specks on the dyed fabric. Studies to predict white specks from bale fiber measurements are underway. Initially a reliable method for measuring white specks is needed. Several systems have been evaluated and are reported here. The systems accuracy was compared using fiber from the US Extreme Variety Study, which was grown specifically to have different levels of white specks. This paper sets out the experimental work and analysis undertaken to develop and validate a system for reliably quantifying the amount of white specks in a woven fabric. Four image analysis systems are compared. This includes two industrial imaging systems (Cambridge and Optimas)2 and two systems specifically developed for white speck analysis (Cotton Incorporated’s prototype and AutoRate). The Cambridge system was too sensitive for this application, and the Cotton Incorporated system was found to have drift in the data over time so that the problem could not be identified. The Optimas system is time consuming and not accurate enough for this application. The AutoRate system gives the most accurate measurements of white specks in the minimal amount of time, with minimal operator error, of all of the systems studied and is currently being used in developing prediction of white specks from bale fiber properties.

Automatic detection of seed coat fragments in cotton fabrics

“…The DP-90 had a micronaire of 4.0 while the STV-825 had a micronaire of 3.7 (see Figure 1). 10 Full size production equipment was used throughout the study. The cottons were processed identically from field to fabric, so the varietal effects could easily be discerned.…”

“…They passed through a hopper, Superior Cleaner and two beater sections of the picker and then were chute fed to the cards. 10 The lots from each variety were single carded, process cotton into 60 grain (gr) card sliver. Carding took place at 27.2 kg/h (60 lbs/ hr).…”

“…It was called the US Extreme Variety Study (EVS). 10 The cottons were grown in the same field and harvested at the same time with spindle harvesting to eliminate as many confounding variables as possible, such as weathering and soil conditions. Identical processing of bale quantities was employed from field to fabric and full warps were made for each variety, so the final fabrics reflected varietal differences only.…”

Measurements of seed coat fragments in cotton fibers and fabrics

“…The system is expected to replace human evaluation of white specks on dyed fabrics because it provides reliable and repeatable measurements. 32 When the Autorate system was modified by Fabrate, LLC, to measure SCFs (dark specks in greige fabric), a new digital camera with a built-in flash was installed for a higher pixel resolution and more uniform lighting (Figure 6). The resolution of this camera is 10 times higher resolution (10 Megapixels) than the previous camera, and its flash largely eliminates 'hot spots' seen in the old system.…”

“…SCFs in a fabric appear much darker than the fabric, and therefore detecting SCFs is a procedure of finding dark specks. The dark speck-counting program is essentially the same as the ones used for white speck counting, 32 except that the image needed to be converted into grayscale and inversed before the counting. The threshold for the minimal size of valid dark specks was determined with hand-count results.…”