Segmentation

From the saliency plot for the two pear example we would like to segment out separately the contours bounding the two pears. One might think of simply thresholding the edge saliencies. However, the edge saliencies for the edges in the two contours are comparable. Hence, we cannot cleanly segment out one contour from the other with a simple threshold. Instead we use additional information provided by the link saliencies to trace out contours given a starting edge. The link saliency from an edge to another edge gives the likelihood that smooth closed contours pass through the two edges in succession. If we start from the most salient edge (denoted by the small circle), we can use the link saliencies to determine the other edges that are connected to the most salient edge through some smooth closed contour. Hence we can avoid grouping contours that are isolated into the same set. In practice, to reveal successive contours bounding objects, we suppress the current set of salient contours and iterate.

	The first segmentation from the saliency plot with directed edges.

	The second segmentation after suppresing the first salient contour.