Topic
Hadamard transform
About: Hadamard transform is a research topic. Over the lifetime, 7262 publications have been published within this topic receiving 94328 citations.
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TL;DR: An algorithm has been developed for calculating sequency-ordered fast Walsh-Fourier transforms (FWT's) using an additive recursion formula that is fast, computer efficient, and applied to time-dependent spectral analysis of nonstationary phenomena such as speech.
Abstract: An algorithm has been developed for calculating sequency-ordered fast Walsh-Fourier transforms (FWT's) using an additive recursion formula. Sequency-ordered FWT's of an N-dimensioned sampled data set are generated by a summation recursion of FWT's on subintervals of the data set. The algorithm is fast (N log2 N summations), computer efficient, and can be applied to time-dependent spectral analysis of nonstationary phenomena such as speech.
42 citations
01 Dec 2000
TL;DR: A general algorithm for decomposition and compression of grayscale images which exhibits a performance which is competitive and often outperforming some of the methods reported in the literature is developed.
Abstract: We develop a general algorithm for decomposition and compression of grayscale images. The decomposition can be expressed as a functional relation between the original image and the Hadamard waveforms. The dynamic adaptive clustering procedure incorporates potential functions as a similarity measure for clustering as well as a reclustering phase. The latter is a multi-iteration, convergent procedure which divides the inputs into nonoverlapping clusters. These two techniques allow us to efficiently store and transmit a class of half-tone medical images such as magnetic resonance imaging (MRI) of the human brain. Due to the redundant image structure of MRI, obtained after the decomposition and clustering, almost half of the image can be omitted all together. Naturally, the compression rates for this specific type of grayscale image are increased greatly. A run-length coding is performed in order to compress further the retained information from the first two steps. Although all the techniques applied are simple, they represent an efficient way to compress grayscale images. The algorithm exhibits a performance which is competitive and often outperforming some of the methods reported in the literature.
42 citations
TL;DR: A three-parameter family of complex Hadamard matrices of order 6 is presented in this paper, which significantly extends the set of closed-form complex hadamard matrix families of this order.
42 citations
TL;DR: The present paper proposes a digital image watermarking scheme using the characteristics of the human visual system, spread transform technique and statistical information measure, which offers several advantages, such as low loss in image information, greater reliability of watermark detection and higher data hiding capacity at high degree of compression.
42 citations
TL;DR: In this paper, it was shown that the product of the main diagonal entries of A in fact separates the permanent and the determinant of A. The Hadamard determinant theorem is stronger than (1).
Abstract: Here per A denotes the permanent of A : per A = 2 * II?»i **(») where the summation is over the whole symmetric group of degree n. It was announced [ l ] and later proved [2] that per (-4)^det-4 and the Hadamard determinant theorem suggests that the product of the main diagonal entries of A in fact separates the permanent and the determinant of A. In this note we sketch a proof of an inequality that is substantially stronger than (1). Let A{i) denote the principal submatrix of A obtained by deleting row and column i.
42 citations