Correction of over and under exposure images using multiple lighting system

When images are acquired in bright condition, it can cause a loss of highlight details (over exposure) in bright area and a loss of shadow details (under exposure) in dark area. Over and under exposure causes a big problem when people investigate dangerous place like Fukushima nuclear power plant through the camera attached remote control robot. In this paper, we propose a method to correct the over and under exposure image to solve the problem. The image processing consists of four steps. Firstly, multiple images are acquired by alternately turning on and off each illumination which set in different positions. Then the image obtained first is defined as input image 1, the image obtained second is defined as input image 2 and the image obtained N-th is defined as input image N. Secondly, luminance of the images is corrected. Thirdly, over and under exposure regions in the image are extracted from the input image 1. Finally, the over and under exposure regions in the input image 1 are compensated by other images. The results show that the over and under exposure regions in the input image are recovered by our proposed method. (author)