In this scene, Andy sits calmly on the ground, leaning against the prison wall, deep in thought. This gives the audience a feeling of suspense, as to the right of the frame Red enters from the left. In a wide-angle shot, the prison wall casts a diagonal line of shadow that divides the frame in half, leaving Andy sitting coldly in the shadow. As the scene unfolds, Andy's dialogue suggests that he might kill himself, as he puts it, "get busy living, or get busy dying." However, going back to the wide shot, you viewers with a good eye will already know that Andy is choosing life. You'll notice that Andy steps out of the shadow side of the frame and into the light, suggesting that he won't kill himself. Note that Red is left halfway between light and darkness, as he hasn't made his choice yet. This leaves the audience guessing what will happen next, encouraging them to continue watching with suspense, which is a contributing factor to the film's success.