Anstract: In this paper, we present two novel, computationally efficient, practically easy to use and highly effective tone mapping techniques for the display of high dynamic range (HDR) images in low dynamic range (LDR) devices. The first new method, termed hierarchical nonlinear linear (HNL) tone-mapping operator maps the pixels in two hierarchical steps. The first step allocates appropriate numbers of LDR display levels to different HDR luminance intervals according to the pixel populations falling onto the intervals. The second step linearly maps the intervals to theirs allocated LDR display levels. In the developed HNL scheme, the assignment of LDR display levels to the HDR luminance intervals is controlled by a very simple and flexible formula with a single adjustable parameter. The second new method, termed the tree structured linear to equalization mapping (TS-LEM) HDR tone-mapping operator clusters the high dynamic range pixels in a hierarchical manner. A single parameter effectively controls the clustering in a computationally highly efficient way, which elegantly renders the mapping ranging from linear scaling to histogram equalization in a seamless manner. Compared with tone mapping operators involving spatial processing, our new methods are computationally more efficient and have far fewer parameters users have to set thus making them much easier to use. Compared with other tone reproduction curve based operators, our methods are much more flexible and effective. Experimental results further demonstrate that the performances of our techniques compare very favorably with state of the art while having the advantages of being computationally simple and practically easy to use. We also demonstrate that our new operators can be used for the effective enhancement of ordinary (8 bits per pixel/gray-scale or 24 bits per pixel/color) images