Gradient Adaptive Image Restoration and Enhancement

Various methods have been proposed for image enhancement and restoration. The main difficulty is how to enhance the structures uniformly while suppressing the noise without artifacts. In this paper, we tackle this problem in the gradient domain instead of the traditional intensity domain. By enhancing the gradient field, we can enhance the structure uniformly without overshooting at the boundary. Because the gradient field is very sensitive to noise, we apply an orientationisotropy adaptive filter to the gradient field, suppressing the gradients in the noise regions while enhancing along the object boundaries. Thus we obtain a modulated gradient field, which is usually not integrable. We reconstruct the enhanced image from the modulated gradient field with least square errors by solving a Poisson equation. This method can enhance the object contrast uniformly, suppress the noise with no artifacts, and avoid setting stopping time as in PDE methods. Experiments on noisy images show the ...

• Type: Conference
• Year: 2006
• Where: ICIP
• Authors: Hongcheng Wang, Yunqiang Chen, Tong Fang, Jason Tyan, Narendra Ahuja
• Keywords: Gradient Domain, ICIP 2006, Image Processing, Modulated Gradient Field, Noise Regions, Orientationisotropy Adaptive Filter, Traditional Intensity Domain