Jack Vartoogian can usually be seen hovering around Summer Stage in Central Park and jazz, blues and world music gigs around the city and country. Vartoogian stands with one of the 19 photos of blues musicians that he and his wife Linda Vartoogian took and that are on display at the World Financial Center. The exhibit features Ray Charles, Aretha Franklin, John Lee Hooker, Koko Taylor, Johnny Winter, and other blues greats and runs through August 14.