Andrzej Chydzinski

Fast detection and impulsive noise removal in color images

In this paper, a novel approach to the impulsive noise removal in color images is presented. The proposed technique employs the switching scheme based on the impulse detection mechanism using the so-called peer group concept. Compared to the vector median filter and other commonly used multichannel filters, the proposed technique consistently yields very good results in suppressing both the random and fixed-valued impulsive noise. The main advantage of the proposed noise detection framework is its enormous computational speed, which enables efficient filtering of color images in real-time applications.

Self-adaptive algorithm of impulsive noise reduction in color images

In this paper a new approach to the problem of impulsive noise reduction in color images is presented. The basic idea behind the new image filtering technique is the maximization of the similarities between pixels in a predefined filtering window. The improvement introduced to this technique lies in the adaptive establishing of parameters of the similarity function and causes that the new filter adapts itself to the fraction of corrupted image pixels. The new method preserves edges, corners and fine image details, is relatively fast and easy to implement. The results show that the proposed method outperforms most of the basic algorithms for the reduction of impulsive noise in color images.

Fast adaptive similarity based impulsive noise reduction filter

In this paper, we address the problem of impulsive noise reduction in multichannel images. A new class of filters for noise attenuation is introduced and its relationship with commonly used filtering techniques is investigated. The computational complexity of the new filter is lower than that of the vector median filter (VMF). Extensive simulation experiments indicate that the new filter outperforms the VMF, as well as other techniques currently used to eliminate impulsive noise in color images.

On the reduction of impulsive noise in multichannel image processing

A new approach to the problem of impulsive-noise reduction for color images is introduced. The major advantage of the technique is that it filters out the noise component while adapting itself to the local image structures. In this way the algorithm is able to eliminate strong impulsive noise while preserving edges and fine image details. As the algorithm is a fuzzy modification of the commonly used vector median operator, it is very fast and easy to implement. Our results show that the proposed method outperforms all standard algorithms for the reduction of impulsive noise in color images.

Time to Reach Buffer Capacity in a BMAP Queue

In this paper a detailed study is presented on the first time to reach buffer capacity in a queue with batch arrivals and general service time distribution. A flexible analytical model of the input stream, which is the Batch Markovian Arrival Process (BMAP), is assumed. The results include the explicit formula for the Laplace transform of the distribution of the first buffer overflow time and discussion of its computational aspects. In addition, the popular special case of the BMAP queue, which is the batch Poisson arrival queue, is studied. Theoretical results are illustrated via numerical calculations based on IP traffic data.

The oscillating queue with finite buffer

The idea of the recently introduced oscillating queueing system is based on two threshold values. Roughly speaking, the service process in this system is organized in such a way that the queue length is kept between these values. The oscillating queueing system has the advantage of making better use of the available resources and is applicable in many devices which use a single server queueing scheme.It is also a generalization of some cell discarding procedures proposed for ATM networks.In this paper a finite buffer version of the oscillating queueing system is studied. The steady-state characteristics of the systems with Poisson input process (M/G-G/1/N)and with exponential distribution of the service time (G/M-M/1/N) are obtained by means of the potential method. This approach gives explicit and easily implementable formulas. In addition, numerical examples are presented.

The M/G-G/1 Oscillating Queueing System

In this paper oscillating queueing system is studied. Oscillating queueing systems are interesting practical objects and researches in this subject are a natural continuation of previous studies on oscillating stochastic processes. It is shown a powerful method for finding characteristic quantities of queuing systems (potential method). Using this method the steady-state distribution of the length of the queue in the M/G-G/1 oscillating system is found and presented in explicit formula. In addition, a numerical example is given.

Analysis of AQM queues with queue size based packet dropping

Analysis of AQM queues with queue size based packet dropping Queueing systems in which an arriving job is blocked and lost with a probability that depends on the queue size are studied. The study is motivated by the popularity of Active Queue Management (AQM) algorithms proposed for packet queueing in Internet routers. AQM algorithms often exploit the idea of queue-size based packet dropping. The main results include analytical solutions for queue size distribution, loss ratio and throughput. The analytical results are illustrated via numerical examples that include some commonly used blocking probabilities (dropping functions).

On the Remaining Service Time upon Reaching a Given Level in M/G/1 Queues

The ability of effectively finding the distribution of the remaining service time upon reaching a target level in M/G/1 queueing systems is of great practical importance. Among other things, it is necessary for the estimation of the Quality-of-Service (QoS) provided by Asynchronous Transfer Mode (ATM) networks. The previous papers on this subject did not give a comprehensive solution to the problem. In this paper an explicit formula for this distribution is given. This formula is general as it includes any initial level of the length of the queue, any type of service distribution (heavy tails) and any traffic intensity ρ. Moreover, it is easy to use and fast in computation. To show this several numerical examples are presented. In addition, a solution of the similar problem in G/M/1 queues (which is the distribution of the remaining interarrival time) is given.

Transient analysis of the MMPP/G/1/K queue

In this paper the transient behaviour of a finite-buffer queue fed by the Markov-modulated Poisson process is studied. The results include formulas for the transforms of transient queue size distribution, transient full buffer probability and transient delay (workload). Computational issues are discussed and numerical samples presented.