Fiber-image Analysis Part II: Measurement of General Geometric Properties of Fibers

As the second part of the series, this paper describes image-analysis algorithms specially designed for measuring the general geometric properties of fibers, such as diameter, length, crimp, and cross-sectional shape. Fibers are imaged longitudinally or transversely through a CCD camera and/or a scanner. Fiber diameters of longitudinal segments in an image are measured by using a scanning algorithm or a shrinking algorithm. Both algorithms can work for an image in which fiber segments cross over each other, and efforts for sample preparation can therefore be eased and more samples can be contained in one image frame. The structures of staples or single fibers are simplified by their skeletons, which can facilitate the measurement of fiber length and crimp. A polynomial-fitting technique is utilized to estimate the natural lengths of fibers that are crimped and curled. The paper also describes new procedures for measuring crimp descriptors and reviews the methods for fiber cross-sectional measurements based on fiber boundaries.