Showing papers on "S transform published in 1990"

Enhancement of high spectral resolution remote-sensing data by a noise-adjusted principal components transform

Abstract: High-spectral-resolution remote-sensing data are first transformed so that the noise covariance matrix becomes the identity matrix. Then the principal components transform is applied. This transform is equivalent to the maximum noise fraction transform and is optimal in the sense that it maximizes the signal-to-noise ratio (SNR) in each successive transform component, just as the principal component transform maximizes the data variance in successive components. Application of this transform requires knowledge or an estimate of the noise covariance matrix of the data. The effectiveness of this transform for noise removal is demonstrated in both the spatial and spectral domains. Results that demonstrate the enhancement of geological mapping and detection of alteration mineralogy in data from the Pilbara region of Western Australia, including mapping of the occurrence of pyrophyllite over an extended area, are presented. >

VLSI architecture for the discrete wavelet transform

Abstract: The wavelet transform is a very effective signal analysis tool for many problems for which Fourier based methods have been inapplicable, expensive for real-time applications, or can only be applied with difficulty. The discrete wavelet transform can be implemented in VLSI more efficiently than the FFT. A single chip implementation is described.

Discrete Mellin transform for signal analysis

Abstract: Theoretical wideband studies generally provide expressions involving stretched forms of the signal. This feature complicates implementation of the results and suggests the use of a Mellin transform to process dilations efficiently. A tool for the practical development of this idea is given. The definition, properties, and time-frequency interpretation of the relevant Mellin transform are given. The discretization is developed, leading to a form which can run with any FFT (fast Fourier transform) routine. The advantage of the technique is illustrated by computing broadband radar ambiguity functions and affine time-frequency representations. >

Hilbert transform algorithm for fringe-pattern analysis

Abstract: A new technique for fringe-pattern analysis is described. The technique, based on the Hilbert transform, is highly accurate and computationally efficient.

Optimal image addition using the Wavelet Transform

Abstract: We present a method for optimizing the widely used operation of image addition, while taking into account the distribution of the signal, the noise and the resolution. The method is based on a new image description concept, known as the Wavelet Transform, which enables one to describe a signal of both space and frequency terms. The main properties of this transform are given, as well as a fast computational algorithm (a trous).

Region-oriented transform coding (ROTC) of images

Abstract: The method of transform coding for image-data compression is generalized by regarding transform coding as a least-squares approximation of two-dimensional functions. By an orthogonalization of basis functions with respect to a particular segment shape, a generalized transform coding scheme is derived. The algorithm contains all block-oriented transforms as special cases and allows the construction of new transforms, e.g. polynomial or spline transforms. The theoretical results are converted into coder and decoder structures enabling region-oriented transform coding without a transmission of the orthogonal basis functions for each segment. >

Comparison of the Gabor and short-time Fourier transforms for signal detection and feature extraction in noisy environments

Abstract: Effective signal detection and feature extraction in noisy environments generally depend on exploiting some knowledge of the signal. The short-time Fourier transform and the Gabor transform are two methods that exploit signal envelope information. This paper compares the two transforms and makes the case that the Gabor representation can often be more compact, and may require substantially less computation and storage in some applications. There is a sense in which the Gabor achieves a preferential trade of SNR for resolution, and because of this, one can also expect better signal recognition and feature reconstructions from the Gabor transform in the presence of noise.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Seismic data compression

Abstract: An investigation of low-rate seismic data compression using transform techniques is presented. This study concentrates on discrete orthogonal transforms such as the discrete Fourier transform (DFT), the discrete cosine transform (DCT), the Walsh-Hadamard transform (WHT), and the Karhunen-Loeve transform (KLT). Uniform and subband transform coding schemes are implemented, and comparative results are given for data rates ranging from 150 to 550 b/s. Results are also compared with existing linear prediction techniques. >

Dynamic generalized Hough transform

Abstract: A new algorithm for the Generalized Hough transform is presented The information available in the distribution of image points is used to optimize the computation of the transform The calculated parameters are those associated with a single image point and all other image points in combinations of the minimum number of points necessary to define an instance of the shape under detection The method requires only one dimensional accumulation of evidence Using the algorithm, the transform of sparse images is more efficiently calculated Dense images may be segmented and similarly processed In two dimensions, the method provides a feedback mechanism between image and transform space whereby contiguity of feature points and endpoints of curves may be determined© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only

Entropy measures for texture analysis based on Hadamard transform

Abstract: The implementation of a software texture analysis technique for images based on the entropy of transform components is described. Different images were compared by computing their entropies, resulting in a relative texture measure. Since entropy can be based on the statistics of both gray-level components and frequency components, four entropy computation routines were implemented. The software calculates the entropy of the gray-levels histogram, the frequency components using the fast-Fourier transform (FFT), transform components using the discrete-cosine transform (DCT), and the transform coefficients of the fast-Hadamard transform (FHT). Because of its decrease in computation time and storage requirements, fast Hadamard was chosen as a better transformation. Entropy calculations were tested on different regional sizes in a time-varying imaging system in order to study regional variations of texture. >

Filtering with the fast T transform

Abstract: The T transform is an intermediate transform from which the multidimensional Fourier and Hartley transforms can be calculated. The T transform can be used in place of these two transforms, accelerating the execution times of applications such as filtering of projections and volumes in 3D reconstruction. >

The Frazier-Jawerth transform

Abstract: The Frazier-Jawerth transform (FJT), a simple yet rigorous method for the time-frequency analysis of nonstationary signals, is discussed. The FJT is related to the wavelet transform. Both the FJT and the wavelet methods improve upon the classical methods of time-frequency analysis due to Wigner and Gabor. A tutorial introduction to the FJT is given, and a brief discussion is presented of an example and some applications. >

Transform coding algorithms for seismic data compression

Abstract: An investigation is presented of transform-based seismic data compression. The study concentrates on discrete orthogonal transforms such as the discrete Fourier transform (DFT), the discrete cosine transform (DCT), the Walsh-Hadamard transform (WHT), and the Karhunen-Loeve transform (KLT). Uniform and subband transform coding schemes were implemented, and comparative results are given for data rates ranging from 150 to 550 b/s. These results are also compared to existing linear prediction techniques. >

Performing a 2-dimensional linear transform with a holographic mask

Abstract: Based on the configuration of coherent optical system composed of a holographic mask and two Fourier transform lenses, an approach of performing a 2-dimensional (2-D) linear transform is suggested. The 2-D Walsh-Hadamard transform of order 32 is tested, and the experimental results are given.

Transform-based medical image compression using a recursive preprocessing approach

Abstract: A recursive preprocessing approach to transform-based medical image compression is presented. This preprocessing approach, combined with the cas-cas transform, shows good performance when applied to medical magnetic resonance images (MRIs). Overall, recursive preprocessing significantly improved all transform-based compression schemes tested, with more improvement noted in the fast cas-cas transform (FCCT) than in the fast cosine transform (FCT). By performing a recursive preprocessing step in the space domain before transforming, edge discontinuities are reduced so that energy packing efficiency can be higher. By using the FCCT, a speed advantage is obtained as compared to the commonly used FCT. The preliminary results show that the compression algorithm using the cas-cas transform affords both a higher compression ratio and speedier computation than the conventional cosine transform. >

The Application of Haar Transform in Signature Extraction and Condition Monitoring of Mechanical Systems

Abstract: In this paper, the Haar transform is applied to vibration signal analysis and system condition monitoring. Based on the Haar transform, the "impulse index" is defined and used as the discriminant for the description of vibration signals. The impulse index offers information about the average power intensity compressed in each equivalent sequency group. It can be obtained conveniently and quickly by means of fast computational algorithm of the Haar transform. The computer simulation data of the output signals of nonlinear models with single degree-of-freedom are used to prove the effectiveness of the impulse index. The results are compared with those obtained from FFT power spectral density and are shown to be effective.

Shape and Strain Measurement of 3-D Object Using Fourier Transform Grid Method.

Abstract: A grid method for measuring the shape and strain distribution of 3D objects by using the Fourier transform grid method is presented. In the conventional automated grid method, the position of a line is expressed in an integer, so it is difficult to analyze the accurate position. Using this twodimensional Fourier transform grid method the fault can be overcome by analyzing and interpolating the phase distribution. Using it, the two dimensional grating can be easily scparated to x- and y-grating based on its orthogonality.

Image coding using weighted cosine transform

Abstract: A new orthogonal transform, called weighted cosine transform (WCT), is developed for digital image coding applications. The new transform is characterized. The transform matrix is the weighted version of that in the discrete cosine transform (DCT). Various commonly used criteria based on the one-dimensional and two-dimensional Markov models have shown that the performance of the order-8 and order-16 WCT is better than the DCT and the phase-shift cosine transform (PSCT), which is an improved version of the DCT. A fast computational algorithm for the WCT is also derived, which, however, requires more computational efforts than the DCT. >

Improved circuit for performing the s-transform

Abstract: An improved circuit for performing the S-­transform and inverse S-transform on digital images. Data is fed back so that only one stage of adder/­subtracters is required. The circuit elements have little idle time, making for efficient VLSI implementation.

Amplitude Bounds on Symmetric Function Transform Coefficients

Abstract: Rapid transform of Reitboeck and Brody [1] was the first example of a class of transforms which had some desirable translation-invariance properties. Many such transforms, generally called symmetric function transforms are now available under extended notion of translation-invariance. The transform coefficients generally have different amplitude bounds, even if the input is uniformly amplitude-bounded. Simple rule for obtaining these amplitude bounds is discussed.

Optical Implementation Of The Kittler-Young Transform For Image Classification

Abstract: The Kittler-Young (K-Y) transform is a nonparametric method for feature extraction. The important property of the K-Y transform is that the information of class variances and mean squares are utilized optimally in feature selection. A joint transform correlator (JTC) is used to extract the features of the K-Y transform from input images optically. Making use of these features, classifications are performed on a microcomputer.