The present invention pertains to a process and an apparatus for treating a photosensitive element to form a relief structure suitable for flexographic printing plate. The apparatus comprises an enclosure, a conveyor, a heatable roller with absorbent material conducted over it, and a roller that can significantly smooth or uniformly roughen the relief structure of the flexographic printing plate. Previously selectively cured photosensitive elements are developed by means of the heatable roller by blotting with the absorbent material, and the resulting relief structure is made uniform by way of a smoothing or roughening roller. The flexographic plates produced by the method and apparatus are especially suited to processes that require substantially smoothed or uniformly roughened printing plate surfaces, which are capable of producing better quality printing.