EI - Adaptive Local Tone Mapping Based on Retinex for High Dynamic Range Images.pdf

Abstract --In this paper, we present a new tone mapping technique for high dynamic range images based on the retinex theory. Our algorithm consists of two steps, global adaptation and local adaptation of the human visual system. In the local adaptation process, the Gaussian filter of the retinex algorithms is substituted with a guided filter to reduce halo artifacts. To guarantee good rendition and dynamic pression, we propose a contrast enhancement factor based on the luminance values of the scene. In addition, an adaptive nonlinearity offset is introduced to deal with the strength of the logarithm function’s nonlinearity. Experiments show that our algorithm provides satisfactory results while preserving details and reducing halo artifacts. I. INTRODUCTION The dynamic range of real world scenes is extensively large spanning over four orders from shadows to highlights [1]. Due to its adaptation mechanisms, the human visual system can cope with the real scenes. However, photographs are different from the real scenes, such as daylight outdoor scenes whose dynamic range is vast. The dynamic range of a scene cannot be captured by a conventional camera or a digital camera because of their imperfectness [2]. Although high dynamic range (HDR) images containing the full dynamic range of the real scene can be obtained from differently exposed photographs [3], low