African-Americans have been systematically excluded from positions of real power in Hollywood for decades, with only a handful of exceptions to prove this unfortunate rule. Still, strong images of black experience have made their way into American movies on some occasions. These are the focus of presentations at two influential New York showcases. A program centering on ``The 1970s New Black Cinema,'' at the American Museum of the Moving Image through March 3, includes fare as varied as Melvin Van Peebles's ferocious ``Sweet Sweetback's Baadasssss Song,'' Michael Schultz's antic ``Car Wash,'' and Richard Fleischer's exploitative ``Mandingo.''
``Landmarks, Breakthroughs and Milestones in Black Film History,'' running through March 14 at Film Forum, is even more ambitious. Its chronology runs from the 1920s through the '60s, when pictures came to embrace vastly different views of African-American life in the far reaches of the American landscape.