Automatic counting of people, entering or exiting a region of interest, is very important for both business and security applications. Shopping malls and supermarkets can use this information to identify hourly trafﬁc patterns, to optimize labor scheduling, and to monitor the effectiveness of promotional events. The counting of people is also very important for security purposes. It helps assign accurate number of security personnel at key places, and design efﬁcient evacuation plans. Automatic detection of abnormal behavior and threats in crowded spaces is welcome in this challenge.