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Image and Signal Processing and Analysis, 2001. ISPA 2001. Proceedings of the 2nd International Symposium on

Date 19-21 June 2001

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  • ISPA 2001. Proceedings of the 2nd International Symposium on Image and Signal Processing and Analysis. In conjunction with 23rd International Conference on Information Technology Interfaces (IEEE Cat. No.01EX480)

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  • Author index

    Page(s): 666 - 668
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    Freely Available from IEEE
  • Adaptive shape from focus with an error estimation in light microscopy

    Page(s): 188 - 193
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (512 KB) |  | HTML iconHTML  

    Light microscopy enlarges the viewing angle while decreasing the depth of focus. This leads to mainly blurred images if the specimen being observed consists of significant height changes. In computer vision, solving this problem is known as `shape from focus'. Algorithms exist that perform both the calculation of a sharp image and the recovery of the three dimensional structure of the specimen. In this paper, three classic approaches for detecting sharp image regions are evaluated. Three new so called focus measures are introduced and are compared to the classic approaches. A new adaptive reconstruction scheme for calculating range images as well as sharp images is presented. Experimental results on synthetic and real data demonstrate the performance of the proposed algorithm View full abstract»

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  • A multilevel neural network model for density volumes classification

    Page(s): 213 - 218
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (524 KB) |  | HTML iconHTML  

    The accurate detection of tissue density variation in CT/MRI brain datasets can be useful for analysing and monitoring pathologies with slight differences. In fact, the objective knowledge of density distribution can be related to anatomical structures and therefore the process of monitoring illness and its treatment can be improved. In this paper, we present an approach for the classification of tissue density in three dimensional brain tomographic scans. The proposed approach is based on a hierarchical neural network model able to classify the single voxels of the examined datasets. The approach has been evaluated on both normal and pathological cases selected by an expert neuroradiologist as study cases. The results have shown that the method has a good effectiveness in practical applications and that it can be used for designing a full 3D instrument suitable for supporting the analysis of disease diagnosis and follow-up View full abstract»

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  • Method of myocardial velocities measurements based on combination of echocardiography and Doppler tissue imaging

    Page(s): 232 - 237
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (460 KB) |  | HTML iconHTML  

    This paper describes a new and original strategy for measuring and characterising the left ventricular myocardial motion in terms of velocity measurements. Our method is based on the combination of echocardiographic images and Doppler tissue imaging. It allows decomposition of the complex myocardial wall velocity into three components: rotation, contraction and translation. The results are shown on diagrams of velocities as a function of time; in fact, we found each velocity component for all the images throughout the cardiac cycle. Furthermore, we propose visualizing the results of myocardial wall regional contraction in reconstructed images in pseudo-color. This quantisation of wall motion velocities by ultrasound imaging should be very helpful for physicians in the diagnosis and prognosis of cardiac diseases View full abstract»

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  • Adapted nonlinear multiresolution decomposition with applications in progressive lossless image coding

    Page(s): 609 - 613
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (372 KB) |  | HTML iconHTML  

    We present an adapted nonlinear multiresolution decomposition (with some derivatives) of still images that permits perfect reconstruction. A hierarchical pyramidal decomposition with maximal decimation is used. For one level of decomposition, the input image I is partitioned into two subimages I1 and I2 obtained by downsampling. The subimage I1 is unchanged. The subimage I 2 is replaced by the rounded output Ih of a 2D FIR filter whose coefficients have first been adapted to I and which has the entries I1 and I2. A similar processing is then applied one time to each of the subimages I1 and I2. The nonlinearity introduced by the rounding permits us to perfectly inverse the process, even when inverse filters (which are all ARMA) are not BIBO stable. Applications are given in lossless image coding, with possibility of embedded zerotree coding View full abstract»

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  • Analysis of the output spectrum for direct digital frequency synthesizers in the presence of phase truncation and finite arithmetic precision

    Page(s): 458 - 463
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (440 KB) |  | HTML iconHTML  

    A simple algorithm is presented for the calculation of the output spectrum of direct digital frequency synthesizers (DDFS) in the presence of phase accumulator truncation and finite arithmetic precision. Using no approximations, a simple formula calculates the magnitudes of the spurious noise frequencies (spurs) due to phase accumulator truncation and due to finite precision implementation. Their spectral position is also determined by a simple expression. The derivation process itself provides strong insight into spur magnitude and spectral location, and it makes evident that the set of spurs due to phase word truncation and the set resulting from finite arithmetic precision are disjoint View full abstract»

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  • Filtering echocardiographic image sequences in frequency domain

    Page(s): 238 - 243
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (520 KB) |  | HTML iconHTML  

    This work describes a new method for filtering echocardiographic image sequences, based on the assumption of an almost periodic motion of the cardiac wall. Exploiting the knowledge of the regular motion of the heart can be advantageous with respect to classical filtering methods where no assumption is made on the image dynamics. From the ideal model of a pulsing ring, a mathematical description of the corresponding gray level pattern in time has been derived, and a peculiar feature in the frequency domain has been observed. This feature has been used as the discriminating function in enhancing pixels with higher probability of lying on the ventricular wall trajectory View full abstract»

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  • FSR-LPTV filtering for blind equalization and interference rejection

    Page(s): 616 - 621
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (428 KB) |  | HTML iconHTML  

    We address the problem of synthesizing a blind channel identification and equalization method for digital communications systems, aimed at counteracting also the presence of co-channel or adjacent-channel interference. Owing to the presence of the interfering signal, the minimum mean-square error equalizer turns out to be linear periodically time-varying (LPTV), which is implemented by restoring to its Fourier series representation (FSR). Moreover, by exploiting the cyclic conjugate second-order statistics of the channel output, we propose a new weighted subspace-based channel identification method. Computer simulation results confirm the effectiveness of the proposed technique View full abstract»

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  • Motion estimation operation implemented in FPGA chips for real-time image compression

    Page(s): 399 - 404
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (376 KB) |  | HTML iconHTML  

    Motion estimation is a very computational demanding operation during the video compression process, thus special hardware architectures are required to achieve real-time compression performance. Advantages in increasing complexity, density and speed of programmable logic devices will soon allow us to implement this kind of application specific processor within one programmable chip. This paper evaluates the performance of block matching hardware architectures implemented in Xilinx FPGA. Systolic arrays for a full search algorithm inferred by T. Komarek and P. Pirsch (1989) have been implemented and evaluated in terms of the achieved clock rate and number of occupied FPGA resources. Results show that, with 2D type systolic arrays, it is possible to achieve real-time performance of motion estimation for CIF images even with a moderate capacity (250 k gates) FPGA chip View full abstract»

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  • Two-stage CMA blind multiuser detection for DS-CDMA systems in multipath fading

    Page(s): 622 - 627
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (432 KB) |  | HTML iconHTML  

    We consider the problem of mitigating intersymbol interference (ISI) due to multipath fading as well as multiple-access interference (MAI) in direct sequence code-division multiple-access (DS-CDMA) systems. The proposed multiuser receiver is based on the constant-modulus algorithm (CMA), which is known to provide satisfactory performance in a blind setting. In order to overcome the CMA interference capture problem typical of a multiuser scenario, we propose to adopt a two-stage receiver: in the first stage, partial MAI suppression is achieved by exploiting the desired user signature structure properties; in the second stage, based on CMA, the residual MAI and the ISI are removed, and the desired symbols are reliably recovered. Computer simulations show that, in a severe multipath environment, the proposed blind approach achieves a significant performance gain in comparison with existing blind methods View full abstract»

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  • 3D fractal compression for real-time video

    Page(s): 570 - 573
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (308 KB) |  | HTML iconHTML  

    A method of image sequence encoding is presented, based on fractal compression of 3D data blocks without searching. A simple fractal transform scheme is used that only depends on one real-valued coefficient. We have developed a software codec for the Windows95 operating system, that carries out video streams in real-time. The method can be further developed for application to videoconferencing, videotelephony or streaming video over the Internet View full abstract»

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  • A remark on the interplay between image compression and watermark embedding techniques

    Page(s): 68 - 73
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (516 KB) |  | HTML iconHTML  

    In this work, we investigate the interplay between compression algorithms and watermark embedding techniques. Three different image codecs are applied to a test image watermarked by three distinct watermarking techniques. We find that a match or similarity between the compression and watermarking domain or technique does not result in the best results in any case. On the contrary, the results of compression attacks of this type are extremely hard to predict View full abstract»

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  • Self-matching of stereoscopic images without camera calibration

    Page(s): 176 - 181
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (488 KB) |  | HTML iconHTML  

    To use an uncalibrated stereoscopic head in computer vision applications where the calibration object is not available and the taken images are noisy, we propose an algorithm for the self-matching of stereoscopic images of indoor scenes. We present also a theoretical adaptation to noisy data of the mathematical approach. The stereo matching algorithm has been tested on both synthetic and real images, and the number of lines matched demonstrates the robustness of the geometric method View full abstract»

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  • A computational allegory for V1

    Page(s): 639 - 644
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1364 KB) |  | HTML iconHTML  

    This contribution introduces a computational allegory for V1 in the task of static image coding. It can be considered an extrapolation of previous V1 models based on unsupervised learning but envisaging two new objectives. The first is a contribution to the discussion of the quantity of V1 cells. The second is the estimation of the quantity of cells within a V1 hypercolumn needed to present to higher-levels the early coding of the correspondent retinal image portion. It is broadly accepted that the quantity of V1 cells coding the correspondent retinal image must be sparse (low dimension) but avoiding pure sparsity (dimension one). The concrete value of that (mean) dimension is still an open issue. Consequently, it is opportune to study the question: “what is the dimension of V1 coding?”. An important side effect of a possible answer could be a contribution to justify the large relative quantity of center-symmetric and simple V1 cells in comparison with the quantity of LGN cells. The implemented allegory is based on unsupervised learning. During the learning phase, a dictionary of image blocks is built by using unsupervised learning principals - principal component analysis (PCA), symmetric component analysis (SCA) and independent component analysis (ICA) operating on small learning sets. During coding, the previously learned dictionary is used to perform matching pursuit in order to code new incoming image blocks as linear combinations of some dictionary components. The results so far obtained support a first provocative answer: “a dimension around 4?” View full abstract»

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  • Implementation of Serpent encryption algorithm on 24-bit DSP processor

    Page(s): 411 - 416
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (404 KB) |  | HTML iconHTML  

    Serpent is one of the AES (advanced encryption standard) candidates and it has been implemented on various 8-bit, 16-bit and 32-bit platforms. In this paper, we have investigated various implementation options of Serpent on 24-bit DSP and described specific issues of the 24-bit platform. Today's Digital Rights Management and secure audio distribution systems utilize 24-bit DSPs and therefore efficient implementation of the encryption algorithm on such platform is important View full abstract»

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  • A simple design of sparse signal representations using overlapping frames

    Page(s): 424 - 428
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (336 KB) |  | HTML iconHTML  

    The use of frames and matching pursuits for signal representation are receiving increased attention due to their perceived potential in various signal processing applications. Good design algorithms for block oriented frames have recently been published. Viewing these block oriented frames as generalizations of block oriented transforms, it is natural to seek corresponding generalizations of critically sampled filter banks leading to overlapping frames. Here we show that a large class of overlapping frames can be decomposed into a critically sampled orthogonal filter bank-that can be chosen prior to the design-and a block oriented frame. Based on this, we show that excellently performing overlapping frames can be designed using the already established and simple theory for the design of block oriented frames View full abstract»

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  • Structural subband decomposition: a new concept in digital signal processing

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    Summary form only given, as follows. Polyphase decomposition of a sequence was advanced to develop computationally efficient interpolators and decimators, and has also been used to design computationally efficient quadrature-mirror filter banks. The polyphase decomposition represents a sequence into a set of sub-sequences, called polyphase components. However, the polyphase components do not exhibit any spectral separation. In this presentation, we first review the concept of structural subband decomposition, generalization of the polyphase decomposition, which decomposes a sequence into a set of sub-sequences with some spectral separation that can be exploited advantageously in many digital signal processing applications. We then outline some of the applications of the structural subband decomposition, such as efficient design and implementation of FIR digital filters, development of computationally efficient decimators and interpolators, subband adaptive filtering, and fast computation of discrete transforms View full abstract»

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  • Suppressing the system error in the measurement model of the prediction-based object recognition algorithm: ovarian follicle detection case

    Page(s): 196 - 201
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (484 KB) |  | HTML iconHTML  

    A heuristic procedure for suppressing system error in the measurement model of a prediction algorithm is presented. This error is suppressed by modifying the measurements. The procedure consists of two steps. Firstly the decision whether a measurement should be modified or nor is taken, and secondly, the measurement is actually modified. Mathematical mechanisms are developed for an integration of the modified measurement model into the prediction algorithm. The new algorithm was tested on sequences of ovarian ultrasound images with follicles. The follicles are recognised about 3% more accurately when compared to the results obtained using the basic prediction algorithm View full abstract»

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  • Evaluation of low- and high-cost systems for teleradiology in neurological emergencies

    Page(s): 655 - 656
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    We evaluated our experience in teleradiology for neurological urgencies. In a first period we used a metropolitan area network based on optical fibers connecting the three Tuscan Universities of Pisa Siena and Florence and a wide area of the city of Florence. We connect by this system our University and one general hospital of the city to use the network to transmit with high speed computed tomography images. In a second period we found non-significant differences regarding image quality using a PC-based system directly connected to CT, also if the ISDN line worked with lower speed. We hope that this system network, more easy to use and available in a large part of our hospitals, will be employed in the transmission of this type of image; in this way in most cases we will be able to move the images only and not the patients View full abstract»

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  • Mathematics foundations for signal processing system synthesis through generalized Fibonacci interconnection topologies

    Page(s): 574 - 579
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (440 KB) |  | HTML iconHTML  

    We extend various bit-level and word-level expressions for representation of switching functions, such as SOP, Reed-Muller expressions, arithmetic, and Walsh expressions, to functions used in Fibonacci interconnection topologies. The corresponding Fibonacci decision diagrams (FibDD) are used as graphic representations of these expressions. At the same time, FibDD are used as a data structure to efficiently calculate coefficients in the introduced expressions, and to perform design of related networks. In this way, we provide a base to extend the application of powerful CAD design tools for switching functions to functions in Fibonacci interconnection topologies View full abstract»

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  • Ultrasound and angiographic image compression by cosine and wavelet transforms and its approval in clinical environment

    Page(s): 74 - 79
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (596 KB) |  | HTML iconHTML  

    The investigation results for improving lossy compression techniques for ultrasound cardiac and X-ray angiographic images are presented. The goal was to clarify where the compression process could be improved, and make efforts for its improvement. A lot of wavelet classes were tried for choosing the one best suited for the corresponding image class, which was defined by the image content complexity measure. The analysis of international image compression standards was carried out. Special attention was paid to the algorithmical and high level service structure of a new still image compression standard JPEG-2000. Its open architecture enables the inclusion of some wavelet classes which we would like to suggest for medical images. A set of recommendations for an acceptable compression ratio for different medical image modalities was developed. It was based on a compression study performed by a group of angiologists and cardiologists View full abstract»

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  • Fast SDP design of FIR compaction filters with combined constraints

    Page(s): 518 - 523
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    We propose efficient semidefinite programming methods for designing signal-adapted compaction filters with: (i) spectral mask, and (ii) regularity constraints. In both cases, the initial problem, formulated with the Kalman-Yakubovich-Popov lemma, is transformed by simplifying its dual and the result is an SDP problem with Toeplitz matrices and small number of variables. All resulting methods, which may be gathered in a single unifying formulation, always give the optimal filter. We present experimental evidence showing convenient execution times and good numerical accuracy View full abstract»

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  • Feature extraction from stochastic process samples

    Page(s): 302 - 307
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    To analyse a stochastic process described by samples drawn from different classes, a method for automatic extraction of discriminant features in reduced dimension space is proposed. To be effective, dimension reduction should be achieved with minimum loss of information. The proposed method is based on the search for an optimal regression between representation space and feature space according to class information. Information is measured using a mutual information estimate. A nonparametric entropy estimate and a stochastic distributed optimisation algorithm are used to solve this problem. An experimental study of simulated problems shows the efficiency of the proposed method View full abstract»

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  • Usage-characteristics of the airborne remote sensing system developed at the Faculty of Transport and Traffic Engineering

    Page(s): 388 - 393
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (640 KB) |  | HTML iconHTML  

    The development of an airborne remote sensing system at the Faculty of Transport and Traffic Engineering started in 1998, as support to postgraduate study. The system is intended for the airborne acquisition of data on urban traffic dynamic characteristics, for the acquisition of data on the bottleneck phenomenon in road traffic, for determining the status of vegetation and forests, and for sensing of mine polluted areas. The aircraft Cessna 172R is used as the platform for the gimbal on which more, mutually different sensors can be placed. The characteristics of the Sharp View Cam VL-H420S as the sensor are considered here. The static spatial resolution of the camcorder is determined by means of test bars. Further, the effects of platform disturbance and vibration on the aerial images are considered View full abstract»

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