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Real-time vision-based approach for probe tracking in operating room

International Congress Series 2004年 1268卷 467-472页

作者： Aly A. Farag M.Sabry Hassouna Ayman El-Baz S. Hushek Computer Vision and Image Processing Laboratory Electrical and Computer Engineering University of Louisville 403 Lutz Hall Bldg. Louisville KY 40292 USA Department of Neurological Surgery University of Louisville USA

A hand-held surgical probe is an essential component of any image-guided neurosurgery (IGNS). During the surgical procedure, the IGNS tracks the probe position and displays the anatomy beneath it as three orthogonal image slices on a workstation-based 3D imaging system. Existing IGNS systems use different tracking techniques including mechanical, optical, ultrasonic, and electromagnetic systems. In this paper, we present a new computational vision-based probe tracking technique, which provides both position and orientation. We also propose another new computational vision-based technique to track the patient head and thus compensate for its movement during probing procedure. The proposed system is completely passive, its stereo cameras detect the presence of the probe using available visible light, and reports on their exact location and orientation in patient physical space in real time. We have validated the system using a skull phantom and a hand made probe.

关键词： image-guided neurosurgery Head motion tracking Probe tracking vision tracking

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Discrimination and identification for subpixel targets in hyperspectral imagery

Discrimination and identification for subpixel targets in hy...

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2004 International Conference on image processing, ICIP 2004

作者： Chang, Chein-I. Liu, Weimin Chang, Chein-Chi Remote Sensing Signal and Image Processing Laboratory Department of Computer Science and Electrical Engineering University of Maryland Baltimore County Baltimore MD 21250 Department of Civil and Environmental Engineering University of Maryland Baltimore County Baltimore MD 21250

Spectral measures have been used in material identification and discrimination. They are effective if the spectral signatures are calibrated and not contaminated. However, it may not be true in many real applications, specifically, for mixed pixels and subpixel targets. This paper investigates the issue of discrimination and identification for subpixel targets and further develops sample spectral covariance/correlation matrix-based hyperspectral measures to account for spectral variability within subpixel targets. Two types of measures are of interest and studied, Mahalanobis distance-based hyperspectral measures and matched filter-based hyperspectral measures. In order to substantiate the proposed measures, a real data-based comparative analysis is conducted and compared to two spectral similarity measures, spectral angle mapper (SAM) and spectral information divergence (SID) for performance evaluation. The experiments show that both Mahalanobis distance-based hyperspectral measures and matched filter-based hyperspectral measures work very effectively and outperformed the SAM and the SID in discrimination and identification for subpixel targets. ©2004 IEEE.

关键词： Imaging techniques

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Enhancement of stents using interference of low-frequency ultrasonic echo signals

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Journal of Medical Ultrasonics 2004年第2期31卷 67-73页

作者： Ohashi, Gosuke Ohya, Akihisa Tobise, Kazimobu Akiyama, Iwaki Faculty of Engineering Shizuoka University Hamamatsu Japan Institute of Information Sciences and Electronics University of Tsukuba Tsukuba Japan Shoryo Electronic Corporation Kamakura Japan Faculty of Engineering Shonan Institute of Technology Fujisawa Japan Image Processing and Vision Research Laboratory Department of Electrical and Computer Engineering University of California at Santa Barbara Santa Barbara CA 93106-9560 United States

Purpose. We set out to enhance the imaging of stents used for coronary coarctation surgery without imaging the reticulation of the stent. Because the stent is a reticulated structure, there is a relation between ultrasound wavelength and the interstice reticulation that produces the echo. Methods. First we performed computer simulation by ultrasound frequency of transmitted signals to analyze this relation. Then, instead of controlling the transmitted wave, we processed the returned signals through a band-pass filter because of the difficulty of controlling the transmitted waves of diagnostic ultrasound equipment. Following this, we conducted experiments on an agar gel phantom containing a stent to verify the effectiveness of this method. Results. The simulation confirmed that the stent was apparent when the ultrasonic wavelength equaled the product of an integer and twice the interval of the reticulation of the stent. Application of a band-pass filter of 0.8 to 1.5MHz to the waveform returned from the agar gel phantom containing the stent. Conclusions. The effectiveness of this method in depicting the stent was confirmed. © The Japan Society of Ultrasonics in Medicine 2004.

关键词： Interference Received waveform Signal processing Stent Ultrasonic echography

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Channel-aware rate-distortion optimized leaky motion prediction

Channel-aware rate-distortion optimized leaky motion predict...

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IEEE International Conference on image processing

作者： Zhen Li E.J. Delp Video and Image Processing Laboratory(VIPER) School of Electrical and Computer Engineering Purdue University West Lafayette IN USA

Leaky motion prediction techniques have been developed as a way to trade-off between video coding efficiency and drift error resilience. In this paper, we present a statistical analysis of leaky motion prediction in the presence of channel errors. We assume the encoder has some basic knowledge of the channel such as the channel error pattern and error rate. We derive a closed-form expression of the rate distortion function and find the analytic solution for the leaky motion prediction parameter. Two examples are presented 10 demonstrate the results.

关键词： Rate-distortion Video coding Motion analysis Decoding Bandwidth image coding image reconstruction Resilience image processing Laboratories

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Markov random field estimation of lost DCT coefficients in JPEG due to packet errors

Markov random field estimation of lost DCT coefficients in J...

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IEEE International Conference on image processing

作者： J. Yang E.J. Delp Vidco and Image Processing Laboratory VIPER School or Electrical and Computer Engineering Purdue University West Lafayette IN USA

Interleaving is used before the encoding of source symbols in JPEG to reduce visual artifacts due to lost packets because interleaving distributes the locations of errors. The recovery of lost DCT coefficients in interleaved image compression is investigated in this paper. To restore the lost coefficients, an Maximum a Posteriori (MAP) estimate for the DCT coefficients is proposed. Under the assumption of a Gauss-Markov Random Field (GMRF) model in the pixel domain, the MAP estimate for the lost DCT coefficients is derived.

关键词： Markov random fields Discrete cosine transforms Decoding Interleaved codes image coding Automatic repeat request Streaming media image restoration Laboratories Communication networks

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Adaptive causal anomaly detection for hyperspectral imagery

Adaptive causal anomaly detection for hyperspectral imagery

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Mingkai Hsueh Chein-I Chang Remote Sensing Signal and Image Processing Laboratory Department of Computer Science and Electrical Engineering University of Maryland Baltimore MD USA Remote Sensing Signal and Image Processing Laboratory Department of Computer Science and Electrical Engineering University of Maryland Baltimore MD USA

ISBN: (纸本)0780387422

Anomaly detection finds target pixels whose signatures are spectrally distinct from their surrounding pixels. It is generally performed without prior knowledge. This paper presents an adaptive causal anomaly detector (ACAD) which implements a causal anomaly detector in such a fashion that a target pixel will be removed from the data correlation matrix once it is detected as an anomaly. As a result, it improves the commonly used RX algorithm as well as a recently developed causal RX filter

关键词： Hyperspectral imaging Filters Detectors Covariance matrix Adaptive signal detection Hyperspectral sensors Remote sensing Signal processing image processing Laboratories

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A nested spatial window-based approach to target detection for hyperspectral imagery

A nested spatial window-based approach to target detection f...

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Weimin Liu Chein-I Chang Remote Sensing Signal and Image Processing Laboratory Department of Computer Science and Electrical Engineering University of Maryland Baltimore MD USA

ISBN: (纸本)0780387422

A great challenge of hyperspectral target detection is to detect subtle targets without prior knowledge, particularly, when the targets of interest are insignificant and occur with low probabilities. This work provides a promising alternative to adaptive hyperspectral target detection. It considers a nested spatial window-based target detection (NSWTD) approach for hyperspectral imagery where a set of different spatial windows are nested and implemented to extract targets whose signatures are spectrally and spatially distinct. The use of nested spatial windows is determined by the image pixel resolution and applications. In order to demonstrate the performance of the proposed NSWTD approach, dual nested windows and three nested windows are implemented for computer simulations and real hyperspectral image experiments. The experimental results demonstrate that our proposed NSWTD approach performs effectively and improves a recent adaptive anomaly detector developed by Kwon et al. and the commonly used anomaly detector developed by Reed and Yu, referred to as RX algorithm. Its computation complexity is also very simple.

关键词： Object detection Hyperspectral imaging Hyperspectral sensors Detectors Spatial resolution Remote sensing Signal processing image processing Laboratories computer science

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A new application of texture unit coding to mass classification for mammograms

A new application of texture unit coding to mass classificat...

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IEEE International Conference on image processing

作者： Yuan Chen Chein-I Chang Remote Sensing Signal and Image Processing Laboratory Department of Computer Science and Electrical Engineering University of Maryland Baltimore MD USA

ISBN: (纸本)0780385543

Texture is one of important features of masses in mammograms. A recent texture unit-based texture spectrum approach, referred to as texture unit coding (TUC) has shown promise in texture classification. This paper presents a new application of the TUC to mass classification in mammograms. The TUC generates a texture spectrum for a texture image that can be used to describe the characteristics of masses. It also develops an information divergence (ID)-based discrimination criterion to measure the discrepancy between two texture spectra, a concept yet to explore in texture analysis. The TUC along with ID are further applied to mass classification in mammograms where the minimammographic database provided by the Mammographic image Analysis Society (MIAS) is used for experiments.

关键词： Pixel Breast cancer Application software image coding image texture analysis Spatial databases Helium image generation Histograms Shape

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New texture shape feature coding-based computer aided diagnostic methods for classification of masses on mammograms

New texture shape feature coding-based computer aided diagno...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Y. Chen C.-I. Chang Remote Sensing Signal and Image Processing Laboratory Department of Computer Science and Electrical Engineering University of Maryland Baltimore MD USA

This work presents new texture shape feature coding (TSFC)-based computer aided diagnostic (CAD) classification methods for classification of masses on mammograms. It introduces a new concept of 1.5-order 3-neighbor 3/spl times/3 connectivity to extract texture shape features that can describe multiples of 22.5/spl deg/. In order to effectively utilize these shape features, two new methods of implementing TFSC are further proposed to convert these features to texture feature numbers (TFNs), TFNs in quaternary (TFNq) which expresses a TFN in quaternary expansion and TFNs in product (TFNx ) that represents a TFN in terms of a product. Both TFNq and TFNx can then produce texture shape histograms in the same way that a gray-level histogram is generated for an image. Such a texture shape histogram is further used to generate various shape features of masses on mammograms for classification. In order to demonstrate the promise of our TSFC-based CAD methods, the MiniMammographic database provided by the Mammographic image Analysis Society (MIAS) is used for experiments.

关键词： Shape Feature extraction Histograms image coding Character recognition Remote sensing Signal processing image processing Laboratories computer science

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A uniform projection-based unsupervised classification for hyperspectral imagery

A uniform projection-based unsupervised classification for h...

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Jing Wang Chein-I Chang Remote Sensing Signal and Image Processing Laboratory Department of Computer Science and Electrical Engineering University of Maryland Baltimore County Baltimore MD USA

ISBN: (纸本)0780387422

Orthogonal subspace projection (OSP) has received considerable interest in hyperspectral image classification. It performs well when the complete knowledge of image endmembers is available. In reality, obtaining such prior knowledge is very difficult, if not impossible. This work investigates a variant of OSP, called uniform projection (UP) and presents a UP-based unsupervised algorithm for hyperspectral image classification. It first implements a uniform target detector (UTD) to find a set of interfering signatures, I, then another uniform I-annihilated detector (UIAD) to find desired target signatures. The signatures in I are combined with the UIAD found desired signatures to form a target signatures matrix M which can be used for supervised image classification. In this case, OSP can be used for this purpose. In order to demonstrate the utility of the proposed unsupervised classification technique for hyperspectral imagery, a series of computer simulations and experiments are conducted for analysis.

关键词： Hyperspectral imaging Data mining Hyperspectral sensors image classification Detectors Histograms Remote sensing Signal processing image processing Laboratories

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