Drawn from its permanent collection, the exhibition “I Am . . . Contemporary Women Artists of Africa” highlights these efforts, featuring modern and contemporary work by 27 artists, including some who are internationally recognized, such as Ghada Amer, Zanele Muholi and Wangechi Mutu, and others whose names will probably be unfamiliar to most visitors. About two-thirds of the pieces were acquired since 2014. Most have not previously been shown in Washington.