Abstract: The existing digital image capture device is not competent for the task of recording the vast-varying luminance range in the real world. In this paper, we first introduced the developments of high dynamic range image (HDRI) capture technology and the HDRI encoding format. To display such an HDRI in the traditional display device (CRT, LCD or printer), the dynamic range mismatch between image and display must be overcome by a tone mapping operator (TMO). An ideal TMO must keep a consistent perceptual experience between the displayed image and the real world scene. In recent years, many TMOs have been proposed, we summarized them into two types (global and local) and gave a detailed explanation.