A visitor takes photos at a facial recognition and matching program during China International Big Data Industry Expo 2019 in Guiyang, southwest China's Guizhou Province, May 26, 2019. The expo on big data opened Sunday in Guizhou Province, focusing on the latest innovation of the technology and its applications. The four-day expo will be attended by 448 enterprises from 59 countries and regions, according to the organizing committee. (Xinhua/Yang Wenbin)