NEW ORLEANS (Reuters) - Entertainer Bill Cosby urged New Orleans' black population on Saturday to cleanse itself of a culture of crime as it rebuilds from the devastation caused by Hurricane Katrina last year. Cosby, whose criticism of some aspects of modern African-American culture has stirred controversy in recent years, told a rally headed by black leaders that the city needed to look at the "wound" it had before Katrina struck. "It's painful, but we can't cleanse ourselves unless we look at the wound," Cosby told the rally of about 2,000 people in front of the city's convention center.