“…The topic that is most often used is related to people [29], [26], [30]. Next, there is a tendency for photos concerning places [31], [32], [33], [28], [34], [35], [2] or related to various time periods [5], [29], [28], [36], [37]. Also, it seems that many people prefer to organize their collection based on a specific event or circumstance, such as a wedding, a baptism, a congress, a meeting at the workplace, etc.…”