The dynamic range of the intensity of long-wave infrared (LWIR) cameras are often more than 8bit and its images have to be visualized using histogram equalization and so on. Many visualization methods do not consider effects of noise, which must be taken care of in real situations. We propose a novel LWIR images visualization method based on gradient-domain processing or gradient mapping. Processing based on intensity and gradient power in the gradient domain enables visualizing LWIR images with noise reduction. We evaluate the proposed method quantitatively and qualitatively and show its effectiveness.