A printing apparatus (100) for printing digital images onto a photosensitive medium (140) employing, for exposure energy, a light source (20) that uses various arrays of LEDs (32). The printing apparatus (100) may form the print image using sequential modulation, one color at a time, or by applying all colors simultaneously. Arrangements of discrete LEDs (32) may include high-intensity devices configured with collector cones (41) arranged as a multicone structure (141), with parabolic reflectors (65), or collimating lenses (36). Large area LEDs (46) may alternately be used, arranged on an angled mounting surface (64), for example.