Hybrid Gradient Operation for Tone Mapping of High Dynamic Range Images

Abstract

Tone mapping is a technique for reproducing a low dynamic range (LDR) image from a high dynamic range (HDR) image. In this paper, a systematic framework using an attenuation function for tone mapping is proposed. One good attenuation function should maintain the contrast at highlight region and maintain the luminance at lowlight region. Designing an attenuation function for comfortable scenes is the critical task in this paper. A tone mapping method based on gradient operation is introduced. In the attenuation function, there are two parameters to be specified. The values of these two parameters depend on the magnitude of gradient of an image. Simple spatial global mapping to generate a formal quality LDR image was used in this paper. And then, an adaptive gradient operation is applied for re-enhancing the contrast in high luminance region. The compromise between quality and efficiency is also considered and handled by changing the iterations. Some preliminary results are shown in this paper.