We optimize the noise shaping behavior of color error diffusion by designing an optimized error filter based on a proposed noise shaping model for color error diffusion and a generalized linear spatially-invariant mod...
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We optimize the noise shaping behavior of color error diffusion by designing an optimized error filter based on a proposed noise shaping model for color error diffusion and a generalized linear spatially-invariant model of the human visual system. Our approach allows the error filter to have matrix-valued coefficients and diffuse quantization error across channels in an opponent color representation. Thus, the noise is shaped into frequency regions of reduced human color sensitivity. To obtain the optimal filter, we derive a matrix version of the Yule-Walker equations which we solve by using a gradient descent algorithm.
This paper presents a method of blind source separation that jointly exploits the nonstationarity and temporal structure of sources. The method needs only multiple time-delayed correlation matrices of the observation ...
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This paper presents a method of blind source separation that jointly exploits the nonstationarity and temporal structure of sources. The method needs only multiple time-delayed correlation matrices of the observation data, each of which is evaluated at a different time-windowed data frame, to estimate the demixing matrix. We show that the method is quite robust with respect to the spatially correlated but temporally white noise. We also discuss the extension of some existing second-order blind source separation methods. Extensive numerical experiments confirm the validity of the proposed method.
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)...
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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.
Thepaper proposes a novel method for content-based search in a database of VRML 3D models. The proposed technique is based on a querying-by-3D-model approach. A set of shape-based descriptors are extracted from the re...
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Thepaper proposes a novel method for content-based search in a database of VRML 3D models. The proposed technique is based on a querying-by-3D-model approach. A set of shape-based descriptors are extracted from the reference 3D model and compared to the corresponding descriptors of the VRML models contained in the database. The descriptors used vary from simple geometric measurements such as the aspect ratio or a binary 3D shape mask to more complex and sophisticated shape-based criteria such as the edge paths of each 3D model. Similarity measures are then introduced for the specific descriptors and introduced into a 3D model-matching algorithm. Experimental results are presented, evaluating the performance of the proposed method.
ROC (Receiver Operating Characteristic) analysis has been widely used to evaluate detection performance. It is based on the Neyman-Pearson detection theory, which solves binary hypothesis testing problems. In mixed pi...
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ROC (Receiver Operating Characteristic) analysis has been widely used to evaluate detection performance. It is based on the Neyman-Pearson detection theory, which solves binary hypothesis testing problems. In mixed pixel classification many algorithms that are developed to estimate abundance fractions (of image endmembers) generally produce gray scale images. As a result, they are not directly applied to hypothesis testing problems. Instead of using the standard ROC curve generated by the detection power versus the false alarm probability, a 3-dimensional (3D) ROC curve is developed in this paper for subpixel detection. It is a 3D plot derived from the mean-detection probability versus the mean-false alarm rate with the third dimension specified by abundance fractions produced by subpixel detection algorithms. In order to illustrate the utility of the proposed 3D ROC analysis in subpixel detection, several linear unmixing-based algorithms are used for performance evaluation.
We developed a finger type blood pressure measurement system using a volume oscillometric algorithm. The digital envelope detection filter (EDF) method was applied to volume oscillometric signals which were acquired f...
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We developed a finger type blood pressure measurement system using a volume oscillometric algorithm. The digital envelope detection filter (EDF) method was applied to volume oscillometric signals which were acquired from an air-filled occlusive finger cuff. In the case of using the EDF, we could reduce the difference error and standard deviation by 30-40%.
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 ...
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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.
This paper describes the 'LipTelephone' system, which is being developed under a Greek AMEA research project, with the purpose to serve as a videophone that can also be used by lip readers. This system aims to...
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ISBN:
(纸本)1586030639
This paper describes the 'LipTelephone' system, which is being developed under a Greek AMEA research project, with the purpose to serve as a videophone that can also be used by lip readers. This system aims to combine model-based with traditional coding techniques in order to exploit the information redundancy in a scene of known content, while achieving high fidelity representation in the specific area of interest, which is the speaker's mouth. The recent MPEG-4 coding standard provides the framework, which is employed, for these purposes.
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 defin...
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