There are two natural orderings in signals: temporal order and rank order. There is no compelling reason to explore only one of these orderings, either in the discrete-time or in the continuous-time case. Nevertheless, the concept of rank order for continuous-time signals remains virtually unstudied, which is in striking contrast to the discrete-time case: ranked order discrete-time filters, of...

When selecting a filter for an application, it is often essential to know the behaviour of the filter in presence of contamination. This robustness of a filter is traditionally explored by means of influence function (IF) and change-of-variance function (CVF). However, as these are asymptotic measures there is uncertainty of the applicability of the obtained results to the finite length filters...

This work shows that the following problems are equivalent, both in theory and in practice: • median filtering : given an n-element vector, compute the sliding window median with window size k, • piecewise sorting : given an n-element vector, divide it in n/k blocks of length k and sort each block. By prior work, median filtering is known to be at least as hard as piecewise sorting: with a sing...

Physical quantities referring to angles, like vector direction, color hue, etc., exhibit an inherently periodic nature. Due to this periodicity, digital filters and edge operators proposed for data on the line cannot be applied on such data. In this paper, we introduce filters for angular signals (circular mean, circular median, circular a-trimmed mean, circular modified trimmed mean). Particul...

This paper presents a new motion estimation algorithm to improve the performance of the existing searching algorithms at a relative low computational cost. We try to amend the incorrect and/or inaccurate estimate of motion with higher precision by using adaptive weighted median filtering and its modifications. The median filter is well-known. A more general filter, called the Adaptively Weighte...

Idempotent filters produce a root signal in a single filter pass, i.e., the filter output is invariant to further filterings with the same filter. In this paper median based idempotent filter structures are introduced. Two approaches to generate these filters are studied: weighted median filters and median filter cascades. Two subclasses of n-dimensional idempotent weighted median filters, call...

Visual information transmitted in the form of digital images is becoming a major method of communication in the modern age, but the image obtained after transmission is often corrupted with noise. The received image needs processing before it can be used in applications. This paper represents a robust statistics based filter to remove salt and pepper noise in digital images. The function of the...

A Median filter is used for eliminating Salt & Pepper Impulse noise and Wiener filter is used for eliminating Gaussian noise. This paper presents a hybrid filter for removal of both types of noises. Two Hybrid filters are presented for eliminating Salt and Pepper noise and Gaussian noise simultaneously from a noisy image. The first filter is a combination of a variant of Median filter and Wiene...

This paper addresses the problem of robust filtering in color images. We propose to improve the bilateral filter by using Ordered Weighted Averaging (OWA) filters. Bilateral filter decreases amount of noise preserving edges when filtering. But the results could be strongly affected by the presence of outliers. In this paper, we define the filtering in the framework of fuzzy logic. If the filter...

A super-mean filter (SUMF) is proposed to remove high density salt & pepper noise from digital images. The proposed filter works in two stages, in the first stage the noisy pixels are detected and in the second stage each noisy pixel is replaced by the mean value of noise free pixel of 2×2 matrix. Extensive simulation and experimental results shows that the proposed filter works well consistent...