Tone Mapping for HDR Images with Dimidiate Luminance and Spatial Distributions of Bright and Dark Regions

摘要

This paper proposes a novel tone mapping method in consideration of characteristics of human visual perception for a high dynamic range (HDR) image with dimidiated luminance and spatial distributions of bright and dark regions. In order to represent an HDR image with a low dynamic range (LDR) display, it is necessary to appropriately compress a dynamic range of HDR image by a tone mapping. There are some HDR images which cannot be re-represented with an LDR display precisely by applying a conventional tone mapping method. In this study, we focus on an HDR image with dimidiated luminance and spatial distributions of bright and dark regions as a target image. We assume that human visual perception does not feel a sense of discomfort even if a magnitude relationship between luminance values of pixels near the boundary between bright and dark regions is reversed when these regions are definitely divided according to dimidiated luminance and spatial distributions. Under this assumption, we divide an HDR image into bright and dark regions and apply a different tone mapping function to each region independently. In experiments, we show that the proposed tone mapping method produces the image represented by using a dynamic range effectively. In addition, we confirm that the proposed tone mapping method is useful through subjective evaluation and discuss the features of the HDR images suitable for the proposed method.