A public art project in Boston's Chinatown is spotlighting the impact of development on the lively, historic downtown neighborhood. Life-sized portraits of residents through the neighborhood's long history are going up in plazas and on street corners for about a week starting Sept. 10. Artist Wen-ti Tsen will also set up photo stations to take portraits of current residents, workers and passers-by that will be turned into life-size cutouts, too. Tsen says the project is meant to underscore how the neighborhood remains a place where generations of people have lived and worked. Susan Chinsen, of the Chinese Historical Society of New England, suggests the exhibit provides a ''neutral'' view of the often contentious gentrification debate.