Fig. 16From: Stopping criterion for linear anisotropic image diffusion: a fingerprint image enhancement casePerformance of proposed stopping rule for a low-quality image. A sample image from FVC2004 database is displayed in (a). Its non-uniform illumination image is extracted as shown in (b). The (c) depicted the uniform image. Spatial entropy points for the uniform image are plotted in (d). A piecewise smooth spline was fitted due to noisy nature of the entropy points, and subsequently, its derivative is computed as shown in (e), proving a smoothed entropy-change curve with increasing logarithmic scale. The optimally diffused image stopped at the farthest peak in entropy-change curve is displayed in (f). The contrast-adjusted image through linear stretch is shown in (g). Finally, a 9×9 block-based binarization was used to come up with a clean binary image as depicted in (h)Back to article page