Impulse noise

About: Impulse noise is a research topic. Over the lifetime, 4816 publications have been published within this topic receiving 63970 citations.

Peer region determination based impulsive noise detection

Abstract: A peer region determination (PRD) algorithm for impulsive noise detection in digital images is proposed; it removes random-valued impulsive noise while preserving very fine image details. This algorithm determines the peer region for each pixel adaptively by finding the variation of pixel values in a 5/spl times/5 filter window. If the number of member pixels in the peer region is very small, the pixel being processed is thought to be isolated from other pixels and thus considered as impulsive noise. In addition, this noise detector can be easily modified to perform feature selective filtering. Experimental results show that the proposed noise detection algorithm outperforms other existing non-linear filters and adaptive noise detection based filters in noise removal and image detail preservation. Finally, the concept of the PRD algorithm applied to other image processing applications is discussed.

Performance evaluation of OFDM transmission over impulsive noisy channels

Abstract: Our aim is to investigate the effect of impulsive noise on the performance of an OFDM system The employed model of impulsive noise consists of Bernoulli distributed impulse arrivals and Gaussian distributed impulse amplitudes The bit error rate performance results are provided by means of simulation The effect of changing the number of carriers of the OFDM system, the impulsivity of the noise, different relative powers of the impulsive noise as well as different impulse-shaping filters are investigated and are compared with the additive white Gaussian noise (AWGN) case Results show that for large signal-to-noise ratios (SNR), and, particularly, very impulsive noise, the OFDM system with a large number of carriers can cope with the impulsivity of the noise, and can improve the performance

A square distance-based byte-erasure method for reduced-delay protection of DSL systems from non-stationary interference

Abstract: DSL systems achieve high rate transmission through copper pairs traditionally used for voiceband communication In order to attain high rates, sophisticated system designs are employed to cope with both stationary and non-stationary disturbers In current DSL systems, protection against nonstationary interference, comprising impulse noise and radio frequency ingress (RFI), is achieved using a forward error correction (FEC) scheme consisting of a Reed-Solomon (RS) code and interleaving However, interleaving results in increased end-to-end delay The end-to-end delay can be reduced by taking advantage of the erasure decoding property of RS codes The paper presents a byte-erasure technique that allows erasure decoding to be employed The method locates the possibly erroneous bytes in each RS codeword by comparing the square distance between each received carrier symbol of the interleaved stream and the closest point of the constellation to which the symbol belongs Thus, the interleaving delay can be reduced by a factor up to 2 when impulse noise impairs transmission The method can also be applied to systems affected by both impulse noise and RFI, since it can distinguish between the two sources of non-stationary interference Finally, no change is required at the transmitter, and hence compatibility with currently deployed systems is guaranteed A DMT-VDSL system is used as a particular example of the achieved reduction of the interleaving delay

An enhanced median filter for removing noise from MR images

Abstract: In this paper, a novel decision based median (DBM) filter for enhancing MR images has been proposed. The method is based on eliminating impulse noise from MR images. A median-based method to remove impulse noise from digital MR images has been developed. Each pixel is leveled from black to white like gray-level. The method is adjusted in order to decide whether the median operation can be applied on a pixel. The main deficiency in conventional median filter approaches is that all pixels are filtered with no concern about healthy pixels. In this research, to suppress this deficiency, noisy pixels are initially detected, and then the filtering operation is applied on them. The proposed decision method (DM) is simple and leads to fast filtering. The results are more accurate than other conventional filters. Moreover, DM adjusts itself based on the conditions of local detections. In other words, DM operation on detecting a pixel as a noise depends on the previous decision. As a considerable advantage, some unnecessary median operations are eliminated and the number of median operations reduces drastically by using DM. Decision method leads to more acceptable results in scenarios with high noise density. Furthermore, the proposed method reduces the probability of detecting noise-free pixels as noisy pixels and vice versa.