Examples of degraded images and their original color images used in the experiment.

<p>(A) Degraded images were created using monochromatic binarization of color images (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115658#s4" target="_blank">Materials and Methods</a>). The examples represent various levels of difficulty. The numerical labels used in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115658#pone-0115658-g001" target="_blank">Figs. 1B</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115658#pone-0115658-g002" target="_blank">2A, 2B</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115658#pone-0115658-g005" target="_blank">5A, 5B</a>, and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115658#pone-0115658-g008" target="_blank">8</a> are consistent with those presented here. (B) The original images of the examples in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115658#pone-0115658-g001" target="_blank">Fig. 1A</a>.