???Face Value: Portraiture in the Age of Abstraction,??? at the National Portrait Gallery April 18 through January 11, features more than 50 paintings, prints, works on paper, and sculptures made between 1945 and 1975, revealing how artists such as Alice Neel, Robert Rauschenberg, Elaine de Kooning, and Andy Warhol approached portraiture when it was out of vogue.