Research On Tone Mapping For High Dynamic Range Images

High dynamic range images are designed to store real-world radiance values. High dynamic range images can represent realistic scene’s luminance and a wide range of color information. HDR images’ dynamic range is far beyond the maximum range of general existing display devices. In order to display the HDR images on the general display devices, compressing HDR images is a very important research of this area.The goal of tone mapping for HDR images is trying its best to preserve the detailed information of original images and avoid producing visual artifacts, while compressing luminance of HDR images. A new tone mapping algorithm based on multi-scale decomposition was designed to solve a high dynamic range (HDR) image displayed on a ordinary display device. The algorithm decomposed a HDR image into multiple scales using a local edge-preserving(LEP) filter to smooth the details of the image effectively, while still retaining the salient edges. Then a dynamic range compression function with parameters was used according to the characteristics of the decomposed layers and the request of compression. By changing the parameters,the coarse scale layer was compressed and the fine scale layer was boosted, resulted in compressing the dynamic range of the image and boosting the details. Finally, by restructuring the image and restoring the color, the image after mapping had a good visual quality. Experimental results demonstrate that the method is better than the other two methods in naturalness, structural fidelity and the quality assessment, moreover, it avoids the halo artifacts which is common problem in the local tone mapping algorithms. The algorithm could be used for the tone mapping of the HDR image.