Fig. 6. Cuttlefish increase number of false edges or reduce visibility of true edges in response to different spatial properties of the substrate. (A–F) First column: original images of animals on substrates S1–S6. Second column: filtered images using edge-detection algorithm, Laplacian of Gaussian (LoG). Third column: the same LoG-filtered images of substrates only (i.e. S1–S6 in Fig. 2). Cuttlefish are difficult to detect, even with LoG operator.