Noise reduction in high dynamic range images

Abstract

Multiple images with different exposures are used to produce a high dynamic range (HDR) image. Sometimes high-sensitivity setting is needed for capturing images in low light condition as in an indoor room. However, current digital cameras do not produce a high-quality HDR image when noise occurs in low light condition or high-sensitivity setting. In this paper, we propose a noise reduction method in generating HDR images using a set of low dynamic range (LDR) images with different exposures, where ghost artifacts are effectively removed by image registration and local motion information. In high-sensitivity setting, motion information is used in generating a HDR image. We analyze the characteristics of the proposed method and compare the performance of the proposed and existing HDR image generation methods, in which Reinhard et al.'s global tone mapping method is used for displaying the final HDR images. Experiments with several sets of test LDR images with different exposures show that the proposed method gives better performance than existing methods in terms of visual quality and computation time.

Ghost and Noise Removal in Exposure Fusion for High Dynamic Range Imaging

“…1 illustrates an example of the ghost artifact in HDRI. Figure 1(a) shows three LDRIs different exposures after image registration [11]. Note that illuminations of images and object positions are changed according to exposure time of the LDRIs.…”

“…Histogram based methods [7,11] classify the intensity values into multi-levels. They regard the region with large difference between the level indices as motion region.…”

“…Min et al's method [11] selectively applies different types of denoising filters to motion regions and static regions in radiance map generation that is based on Debevec and Malik's method [1].…”

“…Then, captured LDRIs are combined into a single HDRI by HDR imaging. However, when LDRIs are combined, several problems can occur due to global and local motions [6][7][8][9] of a camera or an object, and noise [10][11][12] in LDRIs. The ghost artifact and noise are major problems in HDR imaging.…”

“…First, a HDR radiance map, which covers the entire dynamic range of LDRIs, is generated [1]. Generally, in this radiance map generation process, the ghost artifact due to local motion and noise are removed [2,3,11]. Then, the radiance-map is tone-mapped back to a LDR representation to fit the range of display or printing devices [13].…”