Students pick an image and circle regions that appear to draw attention to themselves: salient regions.

The instructor runs the images through the Itti-Koch saliency algorithm, which marks pixels that ought to jump out at viewers because they represent regions that are different from their surroundings.

Instructions given to students

The algorithm identifies image regions that stand out based on several basic visual features, including color, intensity and edge orientation.

It sometimes appears that the algorithm is picking out complex objects that are similar to what humans ultimately notice …

… however, the algorithm actually works in “local” fashion based on small, often meaningless visual differences.