Encryption of medical images based on the cosine number transform

JB Lima, F Madeiro, FJR Sales - Signal Processing: Image Communication, 2015 - Elsevier
In this paper, we introduce a novel scheme for encryption of medical images. The technique
is based on the cosine number transform, a mathematical tool whose application requires …

Image encryption based on the finite field cosine transform

JB Lima, EAO Lima, F Madeiro - Signal Processing: Image Communication, 2013 - Elsevier
In this paper, a novel image encryption scheme is proposed. The technique involves two
steps, where the finite field cosine transform is recursively applied to blocks of a given …

Finite field trigonometric transforms

JB Lima, RM Campello de Souza - Applicable Algebra in Engineering …, 2011 - Springer
In this paper, the finite field trigonometric transforms (FFTT) are introduced. The FFTT family
includes eight types of cosine transforms and eight types of sine transforms, which are …

Light field image encryption based on steerable cosine number transform

VS Lima, FABS Ferreira, F Madeiro, JB Lima - Signal Processing, 2023 - Elsevier
Light field (LF) images can be represented in many different ways but the most convenient,
in terms of visualization and processing, seems to be as an array of 2D images, that is, a 4D …

Fractional cosine and sine transforms over finite fields

JB Lima, RMC de Souza - Linear Algebra and its applications, 2013 - Elsevier
In this paper, we introduce fractional cosine and sine transforms over finite fields. The basis
for the definition of such transforms, which are respectively referred by the acronyms GFrCT …

Fractional Fourier, Hartley, cosine and sine number-theoretic transforms based on matrix functions

PHES Lima, JB Lima… - Circuits, Systems, and …, 2017 - Springer
In this paper, we introduce fractional number-theoretic transforms (FrNTT) based on matrix
functions. In contrast to previously proposed FrNTT, our approach does not require the …

Cosine transforms over fields of characteristic 2: fast computation and application to image encryption

JB Lima, ES da Silva, RMC de Souza - Signal Processing: Image …, 2017 - Elsevier
In this paper, we introduce a fast algorithm for computing cosine transforms over fields of
characteristic 2 (FFCT). Such transforms, which were recently proposed in the literature, are …

Matrices for Generating Orthogonal Eigenvector Bases of Trigonometric Number Transforms

JRDO Neto, JB Lima - 2024 32nd European Signal Processing …, 2024 - ieeexplore.ieee.org
This paper introduces a method based on generating matrices for obtaining trigonometric
number transform (TNT) eigenvectors. We show how to construct such matrices and explain …

Histogram uniformization for digital image encryption

JB Lima, RMC de Souza - 2012 25th SIBGRAPI Conference on …, 2012 - ieeexplore.ieee.org
In this paper, histogram uniformization of digital images by means of the finite field cosine
transform (FFCT) is examined. The approach consists in dividing the image into blocks and …

[HTML][HTML] Cosine transforms over fields of characteristic 2

JB Lima, M Barone, RMC de Souza - Finite Fields and Their Applications, 2016 - Elsevier
In this paper, we introduce cosine transforms over fields of characteristic 2. Our approach
complements previous definitions of finite field trigonometric transforms, which only hold for …