Nonlinear Unsharp Masking Algorithm

Image properties such as contrast, brightness, sharpness, and colorfulness exert a great influence on human perception of image quality. Thus, image enhancement has been assumed an important role in image analysis and computer vision. We propose an efficient algorithm for improving the image sharpness that automatically resolves the well-known out-of-range problem by the means of nonlinear transformation. Adding to that, an optional contrast enhancement step could be applied concurrently to further enhance the image. The proposed algorithm also reduces the halo effect by utilizing the modified hybrid median filter in an iterative manner. A comparative study against other benchmarking methods and experimental results validate the performance of the proposed method.