Figure 3.
Thumbnails showing the image processing steps that were taken during the construction of features τ1 and τ2. (a–c) show a species with relatively narrow areolae (D. insularis). (d–f) show a species with relatively large areolae (O. hirtellus). (g–i) show a species with scabrate ornamentation consisting of granlua (A. odoratum). (a,d,g) show original ×6000 SEM images of each specimen cropped to 40 × 40 pixels. (b,e,h) show quantized images of each specimen with pixels clustered into four groups from low (dark blue) to high (red) intensity. (c,f) show a binary image with pixels in the cluster of lowest intensity as black pixels. (i) shows a binary image with pixels in the two clusters of lower intensity as black pixels. Binary images in (c,f,i) show black pixels as the background and white pixels as the foreground.