Multiresolution Adaptive Image Smoothing

A hierarchical image smoothing method is presented which does not require user specified parameters. For every pixel the largest centered window (7 × 7, 5 × 5 or 3 × 3) containing a constant patch is sought. The selection is made by comparing a locally computed homogeneity measure with its robust global estimate. If the window is declared homogeneous, the pixel is assigned the spatial average. Around discontinuities an adaptive least squares smoothing method is applied for 3 × 3 windows. The performance of the algorithm is compared with several other smoothing techniques for additively corrupted images. The smoothing of synthetic aperture radar images is used as an example for multiplicative noise.