A method and system map high dynamic range images to low dynamic range images. An input set of luminance values can be divided into separate regions corresponding to particular luminance value ranges. A region value can be determined for each region. Based at least in part on the region value, a quantity of range assigned to each region for tone mapping can be dynamically adjusted until each region meets a decision criterion or stopping condition, referred to herein as "concentration." A region can be said to be concentrated if all luminance values therein are within a concentration interval or range. After a region is concentrated, it can be tone-mapped by quantization.