Disclosed is a heat source for radiating heat onto an intermediate printing material transfer element of a printing apparatus. The heat source can include a plurality of heat generating segments disposed along an axis, the plurality of heat generating segments including a first heat generating segment, a second heat generating segment and a third heat generating segment. The second heat generating segment is disposed between the first heat generating segment and the third heat generating segment. The second heat generating segment has a length shorter than a length of the first heat generating segment and shorter than a length of the third heat generating segment. Also disclosed is a printing system that includes the disclosed heat source. Also disclosed is a method of selecting a heat radiating pattern of a heat source.