no code implementations • 25 Feb 2024 • D. F. G. Coelho, R. J. Cintra
This report elaborates on approximations for the discrete Fourier transform by means of replacing the exact Cooley-Tukey algorithm twiddle-factors by low-complexity integers, such as $0, \pm \frac{1}{2}, \pm 1$.
no code implementations • 20 Jun 2023 • V. A. Coutinho, R. J. Cintra, F. M. Bayer
In general, the suggested methods showed competitive performance at a considerably lower computational cost.
no code implementations • 7 Aug 2022 • B. G. Palm, F. M. Bayer, R. J. Cintra
The Rayleigh regression model was recently proposed for modeling amplitude values of synthetic aperture radar (SAR) image pixels.
no code implementations • 29 Jul 2022 • R. J. Cintra, S. Duffner, C. Garcia, A. Leite
The idea is to approximate all elements of a given ConvNet and replace the original convolutional filters and parameters (pooling and bias coefficients; and activation function) with efficient approximations capable of extreme reductions in computational complexity.
no code implementations • 29 Jul 2022 • B. G. Palm, F. M. Bayer, R. Machado, M. I. Pettersson, V. T. Vu, R. J. Cintra
The presence of outliers (anomalous values) in synthetic aperture radar (SAR) data and the misspecification in statistical image models may result in inaccurate inferences.
no code implementations • 29 Jul 2022 • D. F. G. Coelho, R. J. Cintra, F. M. Bayer, S. Kulasekera, A. Madanayake, P. A. C. Martinez, T. L. T. Silveira, R. S. Oliveira, V. S. Dimitrov
This paper introduced a matrix parametrization method based on the Loeffler discrete cosine transform (DCT) algorithm.
no code implementations • 24 Jul 2022 • C. J. Tablada, T. L. T. da Silveira, R. J. Cintra, F. M. Bayer
In this paper, two 8-point multiplication-free DCT approximations based on the Chen's factorization are proposed and their fast algorithms are also derived.
no code implementations • 24 Jul 2022 • B. G. Palm, F. M. Bayer, R. J. Cintra
In this paper, we propose five prediction intervals for the beta autoregressive moving average model.
no code implementations • 23 Jul 2022 • B. G. Palm, D. I. Alves, M. I. Pettersson, V. T. Vu, R. Machado, R. J. Cintra, F. M. Bayer, P. Dammert, H. Hellsten
This paper presents five different statistical methods for ground scene prediction (GSP) in wavelength-resolution synthetic aperture radar (SAR) images.
no code implementations • 19 Jul 2022 • Arjuna Madanayake, Viduneth Ariyarathna, Suresh Madishetty, Sravan Pulipati, R. J. Cintra, Diego Coelho, Raíza Oliveira, Fábio M. Bayer, Leonid Belostotski, Soumyajit Mandal, Theodore S. Rappaport
Arithmetic complexity due to multiplication is reduced from the FFT complexity of $\mathcal{O}(N\: \log N)$ for DFT realizations, down to zero, thus yielding a 46% and 55% reduction in chip area and dynamic power consumption, respectively, for the $N=32$ case considered.
no code implementations • 12 Jul 2022 • A. Madanayake, R. J. Cintra, N. Akram, V. Ariyarathna, S. Mandal, V. A. Coutinho, F. M. Bayer, D. Coelho, T. S. Rappaport
These approximate DFT (ADFT) algorithms have significantly reduced circuit complexity and power consumption compared to traditional FFT approaches while trading off a subtle loss in computational precision which is acceptable for digital beamforming applications in RF antenna implementations.
no code implementations • 5 Jun 2022 • B. G. Palm, D. I. Alves, V. T. Vu, M. I. Pettersson, F. M. Bayer, R. J. Cintra, R. Machado, P. Dammert, H. Hellsten
Applying AR model for each pixel position in the image stack, we obtained an estimated image of the ground scene which can be used as a reference image for CDA.
no code implementations • 3 Jun 2022 • G. M. Cordeiro, R. J. Cintra, L. C. Rêgo, A. D. C. Nascimento
We propose a new four-parameter distribution for modeling synthetic aperture radar (SAR) imagery named the gamma generalized normal (GGN) by combining the gamma and generalized normal distributions.
no code implementations • 1 Jun 2022 • S. M. Perera, A. Madanayake, R. J. Cintra
An efficient DVM algorithm is proposed to reduce the complexity of radio-frequency (RF) $N$-beam analog beamforming systems.
no code implementations • 1 Jun 2022 • S. M. Perera, A. Madanayake, R. J. Cintra
This paper presents a self-contained factorization for the Vandermonde matrices associated with true-time delay based wideband analog multi-beam beamforming using antenna arrays.
no code implementations • 31 May 2022 • T. L. T. da Silveira, D. R. Canterle, D. F. G. Coelho, V. A. Coutinho, F. M. Bayer, R. J. Cintra
The novel transforms perform close to or outperform the current state-of-the-art DCT approximations.
no code implementations • 31 May 2022 • V. A. Coutinho, F. M. Bayer, R. J. Cintra
In this work, we present a set of multiplierless DHT approximations, which can be implemented with fixed-point arithmetic.
no code implementations • 28 Nov 2021 • A. P. Radünz, T. L. T. da Silveira, F. M. Bayer, R. J. Cintra
The Karhunen-Lo\`eve transform (KLT) is often used for data decorrelation and dimensionality reduction.
no code implementations • 28 Nov 2021 • A. P. Radünz, F. M. Bayer, R. J. Cintra
Because its computation depends on the matrix of covariances of the input signal, the use of the KLT in real-time applications is severely constrained by the difficulty in developing fast algorithms to implement it.
no code implementations • 30 Oct 2021 • H. M. de Oliveira, R. J. Cintra
Discrete and continuous standard windowing are revisited and a a new taper is introduced, which is derived from the normal circular distribution by von Mises.
no code implementations • 4 Aug 2021 • D. F. G. Coelho, R. J. Cintra, A. Madanayake, S. Perera
This paper introduces a collection of scaling methods for generating $2N$-point DCT-II approximations based on $N$-point low-complexity transformations.
no code implementations • 8 Mar 2021 • H. M. de Oliveira, R. J. Cintra
This short note introduces a geometric representation for binary (or ternary) sequences.
Information Theory Signal Processing Information Theory
no code implementations • 21 Aug 2020 • A. Borges Jr., R. J. Cintra, D. F. G. Coelho, V. S. Dimitrov
In this Letter, we propose a low-complexity estimator for the correlation coefficient based on the signed $\operatorname{AR}(1)$ process.
no code implementations • 7 Aug 2020 • R. J. Cintra, H. M. de Oliveira, C. O. Cintra
A new multiplication-free transform derived from DHT is introduced: the RHT.
no code implementations • 5 Jul 2020 • R. J. Cintra
Approximate methods have been considered as a means to the evaluation of discrete transforms.
no code implementations • 19 Jun 2020 • D. R. Canterle, T. L. T. da Silveira, F. M. Bayer, R. J. Cintra
Particularly, the discrete cosine transform (DCT) has proven to be convenient for data compression, being employed in well-known image and video coding standards such as JPEG, H. 264, and the recent high efficiency video coding (HEVC).
no code implementations • 14 Jun 2020 • H. M. de Oliveira, V. V. Vermehren, R. J. Cintra
New orbital 2D-wavelets are introduced for the decomposition of still images, showing that it is possible to perform an analysis simultaneous in two distinct scales.
no code implementations • 8 Aug 2018 • R. S. Oliveira, R. J. Cintra, F. M. Bayer, T. L. T. da Silveira, A. Madanayake, A. Leite
Practical applications in image and video coding demonstrate the relevance of the proposed transformation.
1 code implementation • 2 Feb 2017 • F. M. Bayer, R. J. Cintra
A low-complexity 8-point orthogonal approximate DCT is introduced.
Multimedia Data Structures and Algorithms Applications Computation
no code implementations • 24 Sep 2016 • P. A. M. Oliveira, R. J. Cintra, F. M. Bayer, S. Kulasekera, A. Madanayake, V. A. Coutinho
Image and video compression simulations in popular standards shows good performance of the proposed transform.
no code implementations • 23 Jun 2016 • T. L. T. Silveira, R. S. Oliveira, F. M. Bayer, R. J. Cintra, A. Madanayake
An orthogonal 16-point approximate discrete cosine transform (DCT) is introduced.
no code implementations • 2 Feb 2015 • C. J. Tablada, F. M. Bayer, R. J. Cintra
A new class of matrices based on a parametrization of the Feig-Winograd factorization of 8-point DCT is proposed.
no code implementations • 28 Jan 2015 • P. A. M. Oliveira, R. J. Cintra, F. M. Bayer, S. Kulasekera, A. Madanayake
In this paper, we introduce a low-complexity approximation for the discrete Tchebichef transform (DTT).
no code implementations • 13 Jan 2015 • U. S. Potluri, A. Madanayake, R. J. Cintra, F. M. Bayer, S. Kulasekera, A. Edirisuriya
The proposed transform possesses low computational complexity and is compared to state-of-the-art DCT approximations in terms of both algorithm complexity and peak signal-to-noise ratio.
no code implementations • 25 Feb 2014 • R. J. Cintra, F. M. Bayer
An orthogonal approximation for the 8-point discrete cosine transform (DCT) is introduced.
no code implementations • 24 Feb 2014 • V. A. Coutinho, R. J. Cintra, F. M. Bayer, S. Kulasekera, A. Madanayake
A multiplierless pruned approximate 8-point discrete cosine transform (DCT) requiring only 10 additions is introduced.