The Celtics carried certain images off the floor Friday night, saved on their mental hard drives for a little rumination. There was J.R. Smith’s dunk late in the Game 3 loss, which the New York Knicks swingman punctuated by squaring up to face the end zone crowd at the Garden with a self-satisfied smile. There was Carmelo Anthony’s laugh at Brandon Bass, after the latter slapped the ball out of the former’s hands at the start of a timeout. And then Smith returned with a Flagrant 2 elbow to the chops of Jason Terry, close enough to the Celtics bench that coach Doc Rivers was able to restrain his enraged guard. Terry still wasn’t talking about it yesterday, though he did follow a “no comment” with a “no question” when asked if the play gave him a little extra fuel heading into today’s Game 4. The Celtics, booed off the floor by a crowd that had shown unconditional love for the many first responders and medical personnel in the Garden, dragged the memory from all of these sights and sounds into the locker room. Avery Bradley remembered one teammate saying, “Oh, they’re showboating on us, they’re dunking.’ And everybody kind of looked like, ‘Yeah you’re right.’ ” “It was quiet in the locker room,” he said. “Everybody was real mad (Friday night). Nobody was saying anything. Usually Doc talks, and then you hear (Kevin Garnett) and those guys talk to keep us all up, to let us know we’ve got to continue to keep playing hard. (Friday night) right after the game, everybody was pretty quiet, pretty mad.” But anger, like talk, can be greatly overrated. Terry, who had visions of a championship when he signed for three years last summer, admits that his anger, like everyone else’s, needs more than a short fuse. It needs the kind of focus that has been absent in the Celtics’ performance over the last three games.