Curated by University of Chicago professor Wu Hung, a survivor of China's Cultural Revolution, "A Second History" investigates a pre-Photoshop era when anonymous retouchers removed extraneous peasants, disgraced officials, and other undesirable details from Mao-centric compositions. Chinese artist Zhang Dali reproduced 91 photographs, mostly of Chairman Mao, that originally appeared in official Chinese publications over a period of 60 years. Then he paired them with earlier versions, also published, or the original negatives if he could find them. In the cases where an image had multiple sources, he's presented as many of them as possible, scrupulously noting their dates. Mostly the retouchers subtracted elements, rarely adding anything besides color--though someone did put a framed portrait of Mao on the wall of a room full of people in "Under the Leadership of the Working Class, the New Beijing University Fearlessly Advances." As Alain Jaubert wrote in his 1986 book of ideologically doctored shots, Making People Disappear, "faked pictures outlive their creators"; of course our capacity to make virtually undetectable fakes has only increased since then. And lest we dare to trust Dali, a connoisseur of revisionism himself, he's stamped each work with a faux seal reading "China History Photography Archive." Through 7/15: Tue-Sat 10:30-5:30, Walsh Gallery, 118 N. Peoria, 312-829-3312.