检索结果-内蒙古大学图书馆

IEEE International Conference on image processing

作者： N. Damera-Venkata B.L. Evans Halftoning and Image Processing Group Hewlett Packard Laboratories Palo Alto CA USA Embedded Signal Processing Laboratory Department of Electrical and Computer Engineering University of Texas Austin Austin TX USA

Error diffusion halftoning is a popular method of producing frequency modulated (FM) halftones. In FM halftoning the dot size and shape is fixed (equal to one pixel) and the dot frequency is varied in accordance to the graylevel values of the underlying grayscale image. We generalize error diffusion to produce FM halftones with user controlled dot size and shape using block quantization and a block filter in the feedback loop. We call this modified quantization and feedback process block error diffusion. The block filters are designed from well known scalar error filter prototypes and retain their properties. Further, we show that choosing a structured block filter results in an efficient parallel implementation of block error diffusion.

关键词： Frequency modulation Filters Shape control Quantization Pixel Gray-scale Error correction Size control Feedback loop Prototypes

来源：评论

学校读者我要写书评

暂无评论

New algorithms for computing directional discrete Fourier transforms

New algorithms for computing directional discrete Fourier tr...

引用

IEEE International Conference on image processing

作者： M.S. Pattichis R. Zhou B. Raman Department of Electrical and Computer Engineering Image and Video Processing and Communications Laboratory USA Albuquerque High Performance Computing Center University of New Mexico Albuquerque NM USA

New algorithms for computing the discrete Fourier transform (DFT) spectra along different directions are derived and implemented. For computing the DFT spectrum along any given direction (containing N DFT frequencies), a new algorithm is presented that requires N(N-1) additions and a single 1-D FFT. As expected, for a single direction, the directional FFT algorithm is significantly faster than standard 2-D FFT algorithms that compute the entire spectrum (all results are compared against FFTW and FFTPACK). A scalable extension of the unidirectional algorithm for computing the entire DFT spectrum is also derived and implemented. The three most promising features of the new algorithm are that: (i) computation scales nearly linearly with the number of DFT frequencies computed, (ii) the algorithm uses a reduced number of multiplications (yet uses more additions), and (iii) it is more accurate.

关键词： Discrete Fourier transforms Flexible printed circuits High performance computing Frequency Laboratories Electronic mail Scientific computing Fast Fourier transforms Shape MPEG 4 Standard

来源：评论

学校读者我要写书评

暂无评论

The depolarization of radar backscatter from rough surfaces due to surface roughness and slopes

The depolarization of radar backscatter from rough surfaces ...

引用

IEEE International Symposium on Geoscience and remote sensing (IGARSS)

作者： D. Kasilingam D. Schuler Jong-Sen Lee Department of Electrical and Computer Engineering University of Massachusetts Dartmouth North Dartmouth MA USA Remote Sensing Division Naval Research Laboratory Inc. Washington D.C. DC USA

In this study, the depolarization of radar backscatter from rough surfaces is investigated. Short scale surface roughness and long scale surface slopes are shown to contribute towards the depolarization of the co-polarized and cross-polarized components. The study investigates the effects of both these surface parameters on the correlation between the different polarizations. The calculations show that the copolarized coherence, /spl rho//sub hhvv/, is most sensitive to changes in roughness and the circularly polarized coherence, /spl rho//sub rrll/, is sensitive to long scale surface slopes. Results appear to be consistent with measurements from controlled laboratory measurements of backscatter from rough surfaces.

关键词： Rough surfaces Surface roughness Backscatter Polarization Soil measurements Soil moisture Moisture measurement Dielectric constant Radar remote sensing Laboratories

来源：评论

学校读者我要写书评

暂无评论

Color image-based angular map-driven snakes

Color image-based angular map-driven snakes

引用

IEEE International Conference on image processing

作者： A. Dumitras A.N. Venetsanopoulos Speech and Image Processing Services Research Laboratory AT and T Research Laboratories Middletown NJ USA The Edward Rogers Sr. Department of Electrical and Computer Engineering University of Toronto Toronto ONT Canada

We propose a method for shape description of objects in color images. Our method employs angular maps to identify significant changes of color within the image, which are then used to drive snake models. Experimental results show that our angular map-driven snake method not only yields an accurate description of an object shape, but also it is computationally efficient.

关键词： Color Shape image edge detection Laplace equations Laboratories Speech processing image processing USA Councils image retrieval Animation

来源：评论

学校读者我要写书评

暂无评论

Interpreting off-diagonal terms in polarimetric coherency matrix

Interpreting off-diagonal terms in polarimetric coherency ma...

引用

IEEE International Symposium on Geoscience and remote sensing (IGARSS)

作者： J.S. Lee T.L. Ainsworth D.L. Schuler D. Kasilingam W.M. Boerner Remote Sensing Division Naval Research Laboratory Inc. Washington D.C. USA Department of Electrical and Computer Engineering University of Massachusetts Dartmouth USA UIC-EECS/CSN University of Illinois Chicago Chicago IL USA

This paper addresses interpretation of off-diagonal terms in the coherency matrix of polarimetric SAR data. The off-diagonal terms, especially the correlations between copolarization and cross-polarization are frequently ignored in many studies. We will show that this misconception will introduce errors, especially when imaging rugged terrain areas.

关键词： Covariance matrix Azimuth Polarization remote sensing Laboratories Data analysis Matrix decomposition Displays Radar scattering Equations

来源：评论

学校读者我要写书评

暂无评论

remote sensing of surface roughness using polarimetric SAR data

Remote sensing of surface roughness using polarimetric SAR d...

引用

IEEE International Symposium on Geoscience and remote sensing (IGARSS)

作者： D.L. Schuler J.S. Lee D. Kasilingam G. Nesti Remote Sensing Division Code 7263 Naval Research Laboratory Inc. Washington D.C. DC USA Department of Electrical and Computer Engineering University of Massachusetts Dartmouth MA USA EC Joint Research Centre European Microwave Signature Laboratory Varese Italy

The circular polarization coherence, /spl rho//sub RRLL/, is investigated in this paper as a measure of terrain surface roughness. The studies utilized data collected 1) from dielectric surfaces in an anechoic chamber and, 2) from a larger desert test site using P-, L-, and C-band NASA/JPL AIRSAR data. These experimental results, and supporting theory, indicate a sensitive decorrelation of |/spl rho//sub RRLL/| with increasing surface roughness ks. Practical measurement issues and a performance comparison relative to the polarimetric anisotropy A are discussed.

关键词： remote sensing Rough surfaces Surface roughness Dielectric measurements Polarization Anechoic chambers Testing NASA Decorrelation Anisotropic magnetoresistance

来源：评论

学校读者我要写书评

暂无评论

Landsat-7 ETM+ radiometric calibration: two years on-orbit

Landsat-7 ETM+ radiometric calibration: two years on-orbit

引用

IEEE International Symposium on Geoscience and remote sensing (IGARSS)

作者： B.L. Markham J.L. Barker E. Kaita J.A. Barsi D.L. Helder F.D. Palluconi J.R. Schott K.J. Thome R. Morfitt P. Scaramuzza Landsat Project Science Office NASA''s Goddard Space Flight Center Greenbelt MD USA Landsat Project Science Office SSAI/GSFC Greenbelt MD USA Electrical Engineering Department South Dakota State University Brookings SD USA Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA Center of Imaging Science Rochester Institute of Technology Rochester NY USA Remote Sensing Group University of Arizona Tucson Tucson AZ USA Science Department Raytheon-EROS Data Center Sioux Falls SD USA Landsat-7 Image Assessment System Raytheon-EROS Data Center Sioux Falls SD USA

Landsat-7 has been in orbit for 2 years as of April 15, 2001 and operationally providing calibrated data products for 2 years as of June 28, 2001. A radiometric calibration team consisting of scientists and analysts from the Landsat Project Science Office, the Landsat-7 image Assessment System and four universities evaluates the calibration based on on-board and ground-look (vicarious) calibration methodologies. The results are assembled and compared semi-annually and the calibration parameter files are adjusted as necessary. To date the combined results for the reflective bands have not shown any change from pre-launch values. The pre-launch values continue to be used for data processing, with the uncertainty estimated at less than 5%. In the thermal band, the vicarious calibration results indicated a 0.31 W/m/sup 2/ sr /spl mu/m bias in the calibration. This bias results in the ETM+ derived temperatures being about 3K high. The calibration parameter file was updated October 1, 2000 to remove this bias, however the U.S. Landsat Product Generation System (LPGS) software required modification that was not incorporated until December 20, 2000. All LPGS data products generated since this date have the correct thermal band calibration, regardless of image acquisition date, with uncertainties at approximately the 1% level.

关键词： Satellites remote sensing Radiometry Calibration Uncertainty image analysis Educational institutions Assembly Data processing Temperature

来源：评论

学校读者我要写书评

暂无评论

A method for restoration of low-resolution document images

引用

International Journal on Document Analysis and Recognition 2000年第4期2卷 200-210页

作者： Thouin, Paul D. Chang, Chein-I Department of Defense Fort Meade MD 20755 United States Remote Sensing Signal and Image Processing Laboratory Department of Computer Science and Electrical Engineering University of Maryland Baltimore County 1000 Hilltop Circle Baltimore MD 21250 United States

image restoration using resolution expansion is important in many areas of image processing. This paper introduces a restoration method for low-resolution text images which produces expanded images with improved definition. This technique creates a strongly bimodal image with smooth regions in both the foreground and background, while allowing for sharp discontinuities at the edges. The restored image, which is constrained by the given low-resolution image, is generated by iteratively solving a nonlinear optimization problem. Low-resolution text images restored using this technique are shown to be both quantitatively and qualitatively superior to images expanded using the standard methods of linear interpolation and cubic spline expansion. Experimental results demonstrate that text images created by this new algorithm improve optical character recognition accuracy more than images obtained by existing expansion methods. © 2000 Springer-Verlag Berlin Heidelberg.

关键词： Restoration

来源：评论

学校读者我要写书评

暂无评论

Unsupervised fully constrained squares linear spectral mixture analysis method for multispectral imagery

Unsupervised fully constrained squares linear spectral mixtu...

引用

IEEE International Symposium on Geoscience and remote sensing (IGARSS)

作者： D.C. Heinz 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

Subpixel detection and quantification of materials in multispectral imagery presents a challenging problem due to a relatively low number of spectral bands available for analysis in which case the number of spectral bands may be less than the number of materials to be detected and quantified. The problem is even more difficult when the image scene is unknown and no prior knowledge is available. Under this circumstance, the desired information must be obtained directly from the image data. The authors present an unsupervised least squares-based linear mixture analysis method coupled with a band expansion technique for multispectral image analysis. This method allows the authors to extract necessary endmember information from an unknown image scene so that the endmembers present in the image can be detected and quantified. The band expansion technique creates additional bands from the existing multispectral bands using band-to-band nonlinear correlation. These expanded bands ease the problem of insufficient bands in multispectral imagery and can improve and enhance the performance of the proposed method. The experimental results demonstrate the advantages of the proposed approach.

关键词： Least squares methods Spectral analysis Multispectral imaging Layout image analysis Vectors Hyperspectral sensors Hyperspectral imaging Pixel Least squares approximation

来源：评论

学校读者我要写书评

暂无评论

A target-constrained interference-minimized filter for subpixel target detection in hyperspectral imagery

A target-constrained interference-minimized filter for subpi...

引用

IEEE International Symposium on Geoscience and remote sensing (IGARSS)

作者： Hsuan Ren 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

Due to significantly improved high spatial and spectral resolution hyperspectral sensors can now uncover many material substances which cannot be resolved by multispectral sensors. However, this also comes at a price that many unknown and unidentified signal sources, referred to as interferers may also be extracted unexpectedly. Such interferers generally introduce additional noise effects on target detection and its factor must be taken into account. The problem associated with this interference is challenging because interference is generally unknown in nature and cannot be identified from an image scene. This paper presents a target-onstrained interference-minimized filter (TCIMF) which does not require to identify interferers, but can minimize the effects caused by interference. In addition, the TCIMF also separates undesired targets from the desired targets so that the TCIMF can eliminate undesired targets while detecting the desired targets and minimizing interfering effects. Most attractively, these three operations can be carried out by a single process in real time implementation.

关键词： Filters Object detection Hyperspectral sensors Layout Hyperspectral imaging Interference constraints image resolution Signal resolution image sensors image analysis

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：