Adaptive nonlinear filters for 2D and 3D image enhancement

Unsharp masking method is a popular approach for image enhancement, in which a highpass version of an image is added to the original one. This method is easy to run, but is very sensitive to noise. Suppressing noise is generally performed with lowpass filters, and leads to edge blurring. So, an approach which is a combination of a nonlinear lowpass and highpass filters is proposed. These filters are based on an adaptive filter mask. We demonstrate that this approach performs noise reduction as well as edge enhancement. It also improves the contrast enhancement in comparison with other methods. These results are illustrated by processing blurred and noisy images. The method is then extended for 3D data processing and used on 3D seismic images. (C) 1998 Elsevier Science B.V. All rights reserved.