A wavelet optimized finite difference (WOFD) method is presented for adaptively solving a class of singularly perturbed elliptic and parabolic problems. The method is based on an interpolating wavelet transform using polynomial interpolation on dyadic grids. Adaptive feature is performed automatically by thresholding the wavelet coefficients. Numerical examples for elliptic and parabolic proble...

In this paper, we present a comparison of two techniques for noise reduction on CT set of projections. We use for filtering the Pointwise Wiener filter and thresholding of the Wavelet coefficients. We use the Anscombe transformation for noise variance stabilization. The Pointwise Wiener filter was computed with an adaptive windowing scheme for the calculation of local estimates. For the thresho...

In recent years wavelet shrinkage denoising has become the method of choice for the denoising of images. However, despite much research a number of questions remain. Which of the many wavelets that exist should one use? How should the threshold be set? and How are features in the image affected by the thresholding operation? This paper explores these issues and argues for the use of non-orthogo...