Results of the fine-structure segmentation of our method and of that of Yang et al. (2018). In panels a–f, the first column is the input image. Columns 2–3 show the segmentation results generated by our algorithm. Columns 4–5 are the results generated by the algorithm of Yang et al. (2018). The purple arrows in the fourth column of panels a and d indicate the representative examples of the penumbra areas that are not recalled by Yang et al. (2018). The green arrows in the fourth column of panels a, b, and f indicate the representative examples of the incorrectly segmented umbra areas by Yang et al. (2018). The orange arrows in the fourth column of panel f indicate the representative examples of pores that Yang et al. (2018) could recall, but our method could not.