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IEEE 1992 ULTRASONIC SYMP

作者： FERRARA, KW ALGAZI, VR LIU, J Center for Image Processing and Integrated Computing University of California Davis 95616 CA United States Department of Electrical and Electronic Engineering California State University Sacramento 95819 CA United States

ISBN: (纸本)0780305620

In the presence of intervening tissue and frequency dependent scattering, and the context of color flow mapping, the performance of color flow estimation strategies is compared. Intervening tissue has previously been shown to act as a low pass filter for the transmitted waveform, and the scattering response of the cells as a high pass filter. Wideband signal transmission is desired in color flow mapping to improve two dimensional spatial resolution. Since narrowband Doppler estimation strategies suffer from a bias that increases with signal bandwidth and the depth of the intervening tissue, wideband estimation strategies should be combined with wideband signal transmission. In this analysis, a wideband maximum likelihood strategy (WMLE), a cross correlation estimator, and the autocorrelator are considered. © 1992 IEEE.

关键词： Tissue

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Object recognition based on projection

Object recognition based on projection

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International Joint Conference on Neural Networks (IJCNN)

作者： S.D. You G.E. Ford Center for Image Processing and Integrated Computing University of California Davis Davis CA USA Center for Image Processing and Integrated Computing University of California슠Davis Davis CA USA

The authors propose a new connectionist model for invariant object recognition. The model has four stages. The first stage obtains projections from the input image plane. The projection features can separate translation and rotation into two independent translations in s and theta , where s and theta are the axes of the transformed domain directions. The first stage of the recognition network is a discrete implementation of the Radon transform. The second stage adopts the Mellin transform to provide scale invariance. The outputs of this stage are translation and scale invariant. To obtain rotation invariance, the Rapid transform is used. Finally, a pattern classification network is used for recognition. In experiments, five exemplars were used to recognize 240 transformed test objects, and very good results were obtained.< >

关键词： Object recognition Discrete transforms Pattern classification Nearest neighbor searches Equations

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Perceptually based coding of monochrome and color still images

Perceptually based coding of monochrome and color still imag...

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Data Compression Conference (DCC)

作者： T.R. Reed V.R. Algazi G.E. Ford I. Hussain CIPIC The Center for Image Processing and Integrated Computing University of California Davis USA

The authors describe a human visual perception approach and report some results for this problem. The approach is based on the differential quantization of images, in which smooth approximations are subtracted from the image prior to quantization. They consider two such approximations. The first one is an approximation by splines obtained from a sparse and fixed subsampled array of the image. The second one segments the image into piecewise constant regions on the basis of the local activity of the image. Both these approximations result in remainders of residual images where large errors are localized in portions of the image of high activity. Because of visual masking the remainder image can now be coarsely quantized without visual impairment to the reconstructed image. The coarsely quantized remainder is now encoded in an error free manner. In such a perceptually based encoding method the mean square error is now dependent on the activity of the image.< >

关键词： image coding Quantization image reconstruction Humans Visual perception image segmentation Color image processing Distortion measurement Degradation

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Space scale analysis for image sampling and interpolation

Space scale analysis for image sampling and interpolation

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International Conference on Acoustics, Speech, and Signal processing (ICASSP)

作者： G.E. Ford R.R. Estes H. Chen CIPIC Center for Image Processing and Integrated Computing University of California Davis Davis CA USA CIPIC Center for Image Processing and Integrated Computing University of California슠Davis Davis CA USA

In image processing operations involving changes in the sampling grid, including increases or decreases in resolution, care must be taken to preserve image structure. Structure includes regions of high contrast, such as edges, streaks, or corners, all indicated by large gradients. The authors consider the use of local spatial analysis for both sampling and interpolation. Anisotropic diffusion is considered as a directional smoothing technique that preserves structure. This is used in conjunction with a method of directional interpolation, which is also based on structure analysis.< >

关键词： image analysis image sampling Interpolation Smoothing methods Anisotropic magnetoresistance Filters image processing image resolution Convolution Filtering

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SPEECH CODING BY THE EFFICIENT TRANSFORMATION OF THE SPECTRAL ENVELOPE OF SUBWORDS

SPEECH CODING BY THE EFFICIENT TRANSFORMATION OF THE SPECTRA...

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INTERNATIONAL CONF ON ACOUSTICS, SPEECH AND SIGNAL processing

作者： ALGAZI, VR IRVINE, D CALDWELL, C READY, M BROWN, K CHUNG, S Speech Research Laboratory CIPIC Center for Image Processing and Integrated Computing University of California Davis Davis 95616 CA United States ESL Inc. Sunnyvale CA United States AST Applied Signal Technology Santa Clara CA United States Centigram San Jose CA United States

ISBN: (纸本)0780305329

We have developed a new signal-dependent representation which captures, with a few KL vectors and transform coefficients, the perceptually and phonetically important structure of the spectral envelope. Together with a mixed excitation strategy with some novel features, this representation has been applied to the analysis, synthesis, and coding of speech with promising results in the 5kbps range. © 1992 IEEE.

关键词： Speech communication

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Comparison of narrowband and wideband color flow estimators in the presence of intervening tissue

Comparison of narrowband and wideband color flow estimators ...

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IEEE Symposium (IUS) Ultrasonics

作者： K.W. Ferrara V.R. Algazi J. Liu Department of Electri and Electronic Engineering California State University Sacramento CA USA Center for Image Processing and Integrated Computing University of California Davis CA USA

In the presence of intervening tissue and frequency dependent scattering, and in the context of color flow mapping, the performance of color flow estimation strategies is compared. Wideband signal tranmission is desired in color flow mapping to improve two-dimensional spatial resolution. Since narrowband Doppler estimation strategies suffer from a bias that increases with signal bandwidth and the depth of the intervening tissue, wideband estimation strategies should be combined with wideband signal transmission. A wideband maximum likelihood strategy (WMLE), a cross correlation estimator, and the autocorrelator are considered. The cross correlation estimator and WMLE are unbiased in the presence of intervening tissue, whereas the traditional Doppler estimator and autocorrelator have a bias which increases with the depth of the intervening tissue. Both wideband estimation techniques provide similar local and global accuracy, with the position and height of subsidiary peaks actually changing in the presence of intervening tissue.< >

关键词： Narrowband Wideband Autocorrelation Frequency dependence Scattering Frequency estimation Signal mapping Spatial resolution Bandwidth Maximum likelihood estimation

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Speech coding by the efficient transformation of the spectral envelope of subwords

Speech coding by the efficient transformation of the spectra...

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International Conference on Acoustics, Speech, and Signal processing (ICASSP)

作者： V.R. Algazi D. Irvine C. Caldwell M. Ready K. Brown S. Chung CIPIC Center for Image Processing and Integrated Computing University of California슠Davis Davis CA USA ESL Inc. Sunnyvale CA USA AST Applied Signal Technology Santa Clara CA USA

The authors have developed a signal-dependent representation which captures, with a few KL vectors and transform coefficients, the perceptually and phonetically important structure of the spectral envelope. Together with a mixed excitation strategy with some novel features, this representation has been applied to the analysis, synthesis and coding of speech with promising results in the 5-kb/s range.< >

关键词： Speech coding Speech synthesis Speech analysis Signal synthesis image coding Karhunen-Loeve transforms Speech processing Sampling methods Interpolation Filters

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Medial axis representation and encoding of scanned documents

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Journal of Visual Communication and image Representation 1991年第2期2卷 151-165页

作者： Brandt, Jonathan W. Jain, Anil K. Ralph Algazi, V. Computer Vision Research Lab CIPIC: The Center for Image Processing and Integrated Computing United States Department of Electrical Engineering and Computer Science University of California Davis CA 95616 United States

The medial axis transform (MAT) is a sparse representation of shape, which, being reversible, has potential for binary image compression. The MAT also provides structural information not accessible with alternative binary image codes. This structural information is often used for line extraction and pattern recognition. Therefore, the MAT occupies an interesting middle ground between lower-level, compressible image codes and higher-level, meaningful image representations. In an attempt to realize this middle ground, a MAT-based coding scheme which respects its structural properties is developed. The MAT-based coding method is applied to the CCITT facsimile test images. The resulting compression is comparable to that of known coding schemes for textual and somewhat better for graphical data. Some simple modifications to improve skeleton coding performance are suggested. To substantiate the claim that the MAT is effective for higher-level processing, the representation is extended to perform line segment and curve extraction. The extraction takes place under the control of a global error tolerance parameter and thus provides a new method to trade off data compression with distortion for binary images. © 1991.

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Directional interpolation of images based on visual properties and rank order filtering

Directional interpolation of images based on visual properti...

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International Conference on Acoustics, Speech, and Signal processing (ICASSP)

作者： V.R. Algazi G.E. Ford R. Potharlanka CIPIC Center of Image Processing and Integrated Computing University of California Davis USA

The goal of this research is to develop interpolation techniques which preserve or enhance the local structure critical to image quality. Preliminary results are presented which exploit either the properties of vision or the properties of the image in order to achieve the goals. Directional image interpolation is considered which is based on a local analysis of the spatial image structure. The extension of techniques for the design of linear filters based on properties of human perception reported previously to enhance the perceived quality of interpolated images is considered.< >

关键词： Interpolation Nonlinear filters Filtering Frequency image analysis Low pass filters image processing image sampling Bandwidth image quality

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Speech recognition using dynamic features of acoustic subword spectra

Speech recognition using dynamic features of acoustic subwor...

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International Conference on Acoustics, Speech, and Signal processing (ICASSP)

作者： K.L. Brown V.R. Algazi Speech Research Laboratory CIPIC Center of Image Processing and Integrated Computing University of California Davis USA

A novel approach for speech signal analysis has been developed that incorporates both steady-state and dynamic spectral features into a unified model. This model has been successfully applied in automatic speech recognition contexts and does not require frame-based optimal search algorithms. The model decomposes an utterance into a chain of acoustic subwords and simultaneously generates a mathematical description of instantaneous acoustic-phonetic features and dynamic transitions. The algorithm was tested using a speaker-dependent limited vocabulary recognition task and achieved higher recognition rates than both vector quantization and hidden Markov models.< >

关键词： Speech recognition Hidden Markov models Speech analysis Signal analysis Steady-state Context modeling Automatic speech recognition Mathematical model Acoustic testing Vocabulary

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