Heatmap Simulator for webpages

Someone came up with an algorythm to show what people look at on your webpage.
Question is what the algorythm is based on, yet so far the results look stunning and agreeable. Very much reminds me of Martin Wattenberg's click-heat-map from about 8 years ago. With the difference that now, human input becomes redundant for this one.

feng-gui.com via Jonathan