We describe a general method for extraction of an image object based on an approximate knowledge of its shape and its position in the image. The method is combination of the watershed approach and neural networks. It ...
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ISBN:
(纸本)085296692X
We describe a general method for extraction of an image object based on an approximate knowledge of its shape and its position in the image. The method is combination of the watershed approach and neural networks. It is applied to high field MR images of a section of a spinal cord for the extraction of the shape of the grey matter.
This paper describes the current status of our program of work in the area of digital image enhancement using wavelet-based multi-scale processing. We are developing an all-wavelet imageprocessing algorithm to enhanc...
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ISBN:
(纸本)085296692X
This paper describes the current status of our program of work in the area of digital image enhancement using wavelet-based multi-scale processing. We are developing an all-wavelet imageprocessing algorithm to enhance the quality of direct digital thoraximages, by the manipulation of the data within scale-specific sub-bands. This method avoids the presentation compromises which may result from the global application of unsharp mask based image enhancement methods which are commonly used in medical imaging. This is achieved by applying specific processing to image components according to their scale. In particular contrast enhancement, de-noising and sharpening stages are all tailored to the noise and feature characteristics of Thoravision digital chest x-ray images. Whilst our experiments to date convince us that processing digital x-ray images within the wavelet domain is a useful tool for improving diagnostic image quality, our concerns now focus on the subtlety of this processing, since it can be prone to artefact generation if applied incorrectly. We are also interested in optimising the way in which wavelet based image enhancement must be presented to our clinical colleagues to meet their diagnostic needs.
In this paper a method that facilitates an iconic query of an image/video database is presented. A query object is characterised by colour and texture properties. A feed-forward neural network is then trained on these...
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ISBN:
(纸本)085296692X
In this paper a method that facilitates an iconic query of an image/video database is presented. A query object is characterised by colour and texture properties. A feed-forward neural network is then trained on these features using the conjugate gradient-descent algorithm. The same characteristics are computed locally for the database images. The trained neural network is then used to test for the similarity between the iconically specified query and the database image descriptors. We show that by carefully selecting the set of descriptors we can significantly reduce the network size whilst not affecting the quality of results obtained.
A new approach to FPGA implementation of two-dimensional discrete wavelet transform is presented. This architecture allow high accurate and sampling rate DWT realization based on FIR filters of substantial length to b...
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ISBN:
(纸本)0819425915
A new approach to FPGA implementation of two-dimensional discrete wavelet transform is presented. This architecture allow high accurate and sampling rate DWT realization based on FIR filters of substantial length to be implemented on current generation FPGAs. The scheme is based on two parallel pipelined linear phase 17-tap FIR filters with common shift register, partial adders and look-up tables as coefficient multipliers with 4-stage pipelined architecture. The transform is realized in three stages controlled by the state machine, where temporary (L and H) and final subimages (LL, LH, HL, and HH) are created. High throughput (1050 MIPS) and external memory controller allow efficient concurrent cooperation with external processors.
In this paper the chirp z-transform is adapted for the spectral reconstruction of a wideband signal. Here, spectral reconstruction is based on the coherent and sequential processing of non-overlapping short-time segme...
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ISBN:
(纸本)0819425834
In this paper the chirp z-transform is adapted for the spectral reconstruction of a wideband signal. Here, spectral reconstruction is based on the coherent and sequential processing of non-overlapping short-time segments. This approach eases hardware implementation in the presence of limited memory allocation and can provide savings in computational effort, In addition, it offers the flexibility of focusing the reconstruction of the spectrum on a narrow spectral band of interest.
Combined use of the x-ray (Radon) transform and the wavelet transform has proved to be useful in application areas such as diagnostic medicine and seismology. In the present paper, the wavelet x-ray transform is intro...
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ISBN:
(纸本)0819425915
Combined use of the x-ray (Radon) transform and the wavelet transform has proved to be useful in application areas such as diagnostic medicine and seismology. In the present paper, the wavelet x-ray transform is introduced. This transform performs one-dimensional wavelet transforms along lines in R-n, which are parameterized in the same fashion as for the x-ray transform. It is shown that the transform has the same convenient inversion properties as the wavelet transform. The reconstruction formula receives further attention in order to obtain usable discretizations of the transform. Finally, a connection between the wavelet x-ray transform and the filtered backprojection formula is discussed.
Identifying the feature areas in head and shoulder image is an important stage in solving the problems present in current telecommunication systems. How the area of the mouth is detected and used to help create a basi...
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ISBN:
(纸本)085296692X
Identifying the feature areas in head and shoulder image is an important stage in solving the problems present in current telecommunication systems. How the area of the mouth is detected and used to help create a basic system for gaining lip synchronization is discussed. A simple system is created where a particular speech phoneme is given. A database is used to identify the most likely corresponding mouth shape. For this process, two codebooks are used: the first codebook gives the relationship between mouth shapes and phoneme characters while the second describes the relation between the speech and image coefficients.
This paper investigates the relationship between the traditional wavelet (or matched filter) detector and the estimator correlator (EC) detector formulated in the wavelet domain. The EC detector is actually a weighted...
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ISBN:
(纸本)0819425915
This paper investigates the relationship between the traditional wavelet (or matched filter) detector and the estimator correlator (EC) detector formulated in the wavelet domain. The EC detector is actually a weighted wavelet detector, weighted by the scattering function that describes the medium and/or model. The wavelet detector is the optimum detector for point objects but it does not incorporate knowledge of the scattering environment. However, when imaging distributed objects, it is advantageous to take a priori information into account. The EC incorporates this information as a weight on the wavelet image and formulates an estimated spreading function which essentially achieves recombination of highlights and multipath energy. It can be shown that the EC reduces to the the wavelet detector when a point object is being imaged.
We present an improved type of image pyramid based on general approximation functions. The type of pyramid proposed maintains the good properties of symmetry and consistent boundary conditions of the Haar pyramid. Mor...
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ISBN:
(纸本)0819425915
We present an improved type of image pyramid based on general approximation functions. The type of pyramid proposed maintains the good properties of symmetry and consistent boundary conditions of the Haar pyramid. Moreover, it is not restricted to a piece-wise constant image model, but allows the use of any generating sequence. The centered topology guarantees a clearly defined up-projection of labels and may be employed in applications for contour detection, object recognition and segmentation. We start by introducing the general discrete framework for the design of least squares pyramids using the standard filtering and decimation tools based on arbitrary basis functions. Our design criterion is to minimize the l(2) norm of the approximation error. We then define the centered pyramid and give explicit filter coefficients for odd and even spline approximation functions. Finally, we compare the centered pyramid to the ordinary one and highlight some applications.
In this paper we present a model-based algorithm for the estimation of three-dimensional motion parameters of an object moving in SD-space. Photometric effects are taken into account by adding different illumination m...
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ISBN:
(纸本)085296692X
In this paper we present a model-based algorithm for the estimation of three-dimensional motion parameters of an object moving in SD-space. Photometric effects are taken into account by adding different illumination models to the virtual scene. Using the additional information from three-dimensional geometric models of the scene leads to linear algorithms for the parameter estimation of the illumination models which are all computationally efficient. Experiments show that the Peak signal Noise Ratio (PSNR) between camera and reconstructed synthetic images can be increased by up to 7 dB compared to global illumination compensation. The average estimation error of the motion parameters is at the same time reduced by 40 %.
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