Abstract: Digital photographic printing apparatus comprises a photographic paper carrier unit (1) for feeding a sheet of photographic paper past the writing head of an optical scanner unit (2). The writing head incorporates an array of light-emitting devices which are controlled by signals from a digital controller unit (3) holding successive sets of partial image data received from a digital image data unit (4). The writing head comprises a light pipe in the form of a solid fused bundle (10) of coherent optical fibers incorporating a tapered region (17) and having a light receiving face (13) and a light transmitting face (12) adjacent the sheet of photographic paper. An array of light-emitting or laser diodes (14) mounted on a printed circuit board (15) adjacent the light receiving face (13).