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 th...
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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.< >
作者:
G.E. FordR.R. EstesH. ChenCIPIC
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 imageprocessing 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 ...
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In imageprocessing 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.< >
This paper proposes 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 rotation ...
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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...
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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 ...
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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 translati...
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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.< >
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 w...
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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.< >
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 desir...
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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.< >
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 bi...
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