Adaptive contrast enhancement using edge-based lighting condition estimation

• Lighting condition estimation using detected edges is presented.
• Transfer function for improvement of local contrast and preservation of structure is proposed.
• Contrast enhancement approach for improvement of global contrast and reduction of artifacts is proposed.

This paper proposes a new approach to image contrast enhancement that improves the perceptual visual quality by considering the lighting condition and minimizing the structural distortion to a tolerable level. The proposed method consists of the following two major steps: lighting condition estimation and contrast enhancement processes. In the first step, the proposed method estimates the lighting condition by calculating the dynamic range along the edges of the image. In the second step, the method adaptively adjusts the luminance by considering both the estimated lighting condition and the order of luminance levels in order to improve the perceptual visual quality. In addition, the method properly reduces the structural distortion. Experimental results show that the proposed method improved the perceptual visual quality of various images by increasing the average structural fidelity, enhancement performance measure, entropy, and tone-mapped image quality index by up to 11%, 133%, 16%, and 11%, respectively, compared to the benchmark methods.