Crumb director Terry Zwigoff’s first film is a true treat: a documentary about the obscure country-blues musician and idiosyncratic visual artist Howard “Louie Bluie” Armstrong, member of the last known black string band in America. As beguiling a raconteur as he is a performer, Louie makes for a wildly entertaining movie subject, and Zwigoff honors him with an unsentimental but endlessly affectionate tribute. Full of infectious music and comedy, Louie Bluie is a humane evocation of the kind of pop-cultural marginalia that Zwigoff would continue to excavate in the coming years.