Two-level optimized tone mapping for high dynamic range images

In this paper, we propose a two-step tone-mapping algorithm to convert a high dynamic range (HDR) image to a low dynamic range (LDR) image. The first step S1 constructs a global tone mapping which optimizes between uniform quantization and histogram equalization. The second step S2 improves the visual quality by optimizing between global operation and local contrast maintenance. Both S1 and S2 can operate independent of each other. Simulation results suggest that proposed tone mapping algorithm can give good visual quality, with S1+S2 better than S1 alone. Simulation results also suggest that proposed S2 can be combined with other existing tone mapping methods to achieve improved local contrast.