Search Results for author: R. J. Cintra

Found 36 papers, 1 papers with code

Discrete Fourier Transform Approximations Based on the Cooley-Tukey Radix-2 Algorithm

no code implementations25 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 $0, \pm \frac{1}{2}, \pm 1$.

Low-complexity Multidimensional DCT Approximations

no code implementations20 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.

Quantization Visual Tracking

Improved Point Estimation for the Rayleigh Regression Model

no code implementations7 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.

regression

Low-complexity Approximate Convolutional Neural Networks

no code implementations29 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.

Face Detection

Robust Rayleigh Regression Method for SAR Image Processing in Presence of Outliers

no code implementations29 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.

Anomaly Detection regression

Low-Complexity Loeffler DCT Approximations for Image and Video Coding

no code implementations29 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.

DCT Approximations Based on Chen's Factorization

no code implementations24 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.

Image Compression

Prediction Intervals in the Beta Autoregressive Moving Average Model

no code implementations24 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.

Prediction Intervals

Wavelength-Resolution SAR Ground Scene Prediction Based on Image Stack

no code implementations23 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.

Change Detection

Towards a Low-SWaP 1024-beam Digital Array: A 32-beam Sub-system at 5.8 GHz

no code implementations19 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.

Fast Radix-32 Approximate DFTs for 1024-Beam Digital RF Beamforming

no code implementations12 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.

Autoregressive Model for Multi-Pass SAR Change Detection Based on Image Stacks

no code implementations5 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.

Change Detection

The Gamma Generalized Normal Distribution: A Descriptor of SAR Imagery

no code implementations3 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.

Efficient and Self-Recursive Delay Vandermonde Algorithm for Multi-Beam Antenna Arrays

no code implementations1 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.

Radix-2 Self-Recursive Sparse Factorizations of Delay Vandermonde Matrices for Wideband Multi-Beam Antenna Arrays

no code implementations1 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.

A Class of Low-complexity DCT-like Transforms for Image and Video Coding

no code implementations31 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.

Low-complexity Three-dimensional Discrete Hartley Transform Approximations for Medical Image Compression

no code implementations31 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.

Image Compression PICO +1

Low-complexity Rounded KLT Approximation for Image Compression

no code implementations28 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.

Dimensionality Reduction Image Compression

Von Mises Tapering: A New Circular Windowing

no code implementations30 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.

Low-complexity Scaling Methods for DCT-II Approximations

no code implementations4 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.

Geometrical Representation for Number-theoretic Transforms

no code implementations8 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

Low-complexity Architecture for AR(1) Inference

no code implementations21 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.

Rounded Hartley Transform: A Quasi-involution

no code implementations7 Aug 2020 R. J. Cintra, H. M. de Oliveira, C. O. Cintra

A new multiplication-free transform derived from DHT is introduced: the RHT.

Decision Making

An Integer Approximation Method for Discrete Sinusoidal Transforms

no code implementations5 Jul 2020 R. J. Cintra

Approximate methods have been considered as a means to the evaluation of discrete transforms.

A Multiparametric Class of Low-complexity Transforms for Image and Video Coding

no code implementations19 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).

Data Compression Image Compression

Multidimensional Wavelets for Scalable Image Decomposition: Orbital Wavelets

no code implementations14 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.

DCT-like Transform for Image Compression Requires 14 Additions Only

1 code implementation2 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

A Class of DCT Approximations Based on the Feig-Winograd Algorithm

no code implementations2 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.

Image Compression

A Discrete Tchebichef Transform Approximation for Image and Video Coding

no code implementations28 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).

Improved 8-point Approximate DCT for Image and Video Compression Requiring Only 14 Additions

no code implementations13 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.

Video Compression

A DCT Approximation for Image Compression

no code implementations25 Feb 2014 R. J. Cintra, F. M. Bayer

An orthogonal approximation for the 8-point discrete cosine transform (DCT) is introduced.

Image Compression

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