نتایج جستجو برای: classical wavelet transforms

تعداد نتایج: 242434  

Journal: :iranian journal of medical physics 0
sh. olumi m.sc. in medical physics, tarbiat modarres university, tehran, iran h. rajabi assistant professor, medical physics dept., tarbiat modarres university, tehran, iran s.r. zakavi associate professor, nuclear medicine dept., imam reza hospital, mashhad university of medical sciences, mashhad, iran e. hajizade associate professor, biostatistics dept., tarbiat modarres university, tehran, iran h. ghiasi m.sc. in medical physics, torfe hospital, tarbiat modarres university, tehran, iran

introduction: one of the major problems in the development of nuclear medicine images is the presence of noise. the noise level in nuclear medicine images is usually reduced by the analysis of imaging data in a fourier transform environment. the main drawback of this environment belongs to low signal to noise ratio in high frequencies because removing noise frequencies may remove data and times...

1997
A. R. Calderbank Ingrid Daubechies Wim Sweldens Boon-Lock Yeo

Invertible wavelet transforms that map integers to integers are important for lossless representations. In this paper, we present an approach to build integer to integer wavelet transforms based upon the idea of factoring wavelet transforms into lifting steps. This allows the construction of an integer version of every wavelet transform. We demonstrate the use of these transforms in lossless im...

1999
Andreas Klappenecker

We show how periodized wavelet packet transforms and periodized wavelet transforms can be implemented on a quantum computer. Surprisingly, we find that the implementation of wavelet packet transforms is less costly than the implementation of wavelet transforms on a quantum computer.

2003
Laurent Duval Truong Q. Nguyen

Algorithms based on wavelet-domain hidden Markov tree (HMT) have demonstrated excellent performance for image denoising. The HMT model is able to capture image features across the scales, in contrast to classical shrinkage that thresholds subbands independently. In this work, we extend the aforementioned results to a lapped transform domain. Lapped Transforms (LT) are -channel linear phase filt...

1999
Juergen Niederholz Carl Taswell

Near-best and best wavelet packet transforms were compared with wavelet transforms for the compression of polysomnograms in a low bitrate telemonitoring application. Near-best wavelet packet transforms provided better overall performance with respect to efficiency of computation and compression, and amenability for use in more sophisticated quality-on-demand algorithms. Keywords— near-best base...

2001
Gheorghe Craciun Raghu Machiraju David Thompson Yootai Kim

In this paper we develop a filter design framework emphasizing feature preservation. We are particularly interested in multiscale filters that can be used in wavelet transforms for large datasets generated by computational fluid dynamics simulations. High-fidelity wavelet transforms can facilitate the visualization of large scientific data sets. However, it is important that salient characteris...

Journal: :Optical Engineering 1992

Watermarking is one of the best solutions for copyright protection and authentication of multimedia contents. In this paper a hybrid scheme is proposed using wavelet and shearlet transforms with singular value decomposition. For better security, Arnold map is used for encryption. Examining the results and comparing with other methods show that this hybrid proposed scheme with simultaneous utili...

2001
Michael D. Adams Rabab Ward

Studied are numerous issues associated with wavelet transforms in the JPEG-2000 Part-1 standard (i.e., ISO/IEC 15444-1). The dynamic range of wavelet transform coefficients and computational complexity of wavelet transforms are examined. Also, the effect of wavelet transforms on coding efficiency is investigated. The information presented herein may prove beneficial to those developing JPEG-200...

Journal: :Journal of Mathematical Analysis and Applications 1998

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