Readability Enhancement of Displayed Images Under Ambient Light
Haonan Su, Cheolkon Jung, Shuyao Wang, Yuanjia Du · IEEE Transactions on Circuits and Systems for Video Technology · 2017
Image quality in mobile displays is considerably influenced by ambient light. In the daylight condition, images on mobile displays are darkly perceived by the human visual system due to the limited dynamic range of display, which causes loss of luminance and details. In this paper, we propose readability enhancement of displayed images under ambient light by enhancing both luminance and details. We design a weighted optimization framework, which contains the data term for luminance enhancement and the gradient term for detail enhancement. In the data term, we use an ambient light nonlinear intensity-transfer function considering display properties, ambient light, and image contents. In the gradient term, we employ a threshold versus intensity adaptation function based on the degree of ambient light adaptation to compensate for gradient distortions. We solve the optimization framework using a numerical solver and achieve image enhancement in displayed images. Experimental results demonstrate that the proposed method significantly improves readability of mobile displays under ambient light by enhancing luminance and details of images.