Image Analysis Tools to Quantify Visual Properties of Hair Fiber Assemblies 326 fibers. The alignment of eyelash fibers was measured using Fourier transform, similar to the method described above for African hair treated with a relaxer. Figure 13 shows two images of eyelashes, untreated and mascara treated, with a view looking down the axis of the cylinder. A section of the image was segmented (Figures 13c and 13d) and Fourier transform was performed on the new image. From the Fourier transform plots (Figures 13e and 13f) we can discern a preferential geometric arrangement for mascara treated eyelashes, which is manifested as two distinct distributions. The untreated sample, on the other hand, provides a weak and scattered distribution in frequency space. Figure 12. Images of (a) untreated and (b) mascara-treated eyelashes mounted on a Teflon cylinder (c) Illustration of important parameters that are measured by image analysis of eyelash photographs