Joint Denoising and Contrast Enhancement of Images Using Graph Laplacian Operator

Images and videos are often captured in poor light conditions, resulting in low-contrast images that are corrupted by acquisition noise. To recreate a high-quality image for visual observation, the captured image must be denoised and contrast-enhanced. Conventional methods perform these two tasks in two separate stages: an image is first denoised, followed by an enhancement procedure. In this paper, we propose to jointly denoise and enhance an image in one unified optimization framework. The crux of the optimization rests on the definition of the enhancement operator, described by a graph Laplacian matrix H. The operator must enhance the high frequency details of the original image without amplifying additive noise. We propose a graph-based low-pass filtering approach to denoise edge weights in the graph, resulting in a more robust estimate of H. Experimental results show that our proposed joint approach can outperform the separate approach in demonstrable image quality.