The basic form of drifting sub-pulses is that of a periodicity whose phase depends (approximately linearly) on both pulse longitude and pulse number. As such, we argue that the two-dimensional Fourier transform of the longitude-time data (called the Two-Dimensional Fluctuation Spectrum; 2DFS) presents an ideal basis for studies of this phenomenon. We examine the 2DFS of a pulsar signal synthesi...

In medicine, there is a still growing interest in non-invasive examination techniques which can depict anatomical structures. Amongst these methods are Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET) and Computerised Tomography (CT). These are all based on the same principle: under a number of angles, a set of line integrals in a plane is measured resulting in a set of proo...

Many signals on Cartesian product graphs appear in the real world, such as digital images, sensor observation time series, and movie ratings on Netflix. These signals are “multidimensional” and have directional characteristics along each factor graph. However, the existing graph Fourier transform does not distinguish these directions, and assigns 1-D spectra to signals on product graphs. Furthe...

This paper presents an innovative way of using the two-dimensional (2-D) Fourier transform for speech enhancement. The blocking and windowing of the speech data for the 2-D Fourier transform are explained in detail. Several techniques of filtering in the 2-D Fourier transform domain are also proposed. They include magnitude spectral subtraction, 2-D Wiener filtering as well as a hybrid filter w...

Abstract—In digital watermarking, a watermark is embedded into a cover text in such a way that the resulting watermarked signal is robust to certain distortion caused by either standard data processing in a friendly environment or malicious attacks in an unfriendly environment. This paper presents a digital image watermarking based on two dimensional discrete cosines transform (DCT2), two dimen...

Many concepts that are used in multi{dimensional signal processing are derived from one{dimensional signal processing. As a consequence , they are only suited to multi{dimensional signals which are intrinsically one{dimensional. We claim that this restriction is due to the restricted algebraic frame used in signal processing, especially to the use of the complex numbers in the frequency domain....

In this work, we describe a frequency domain technique for the estimation of multiple superimposed motions in an image sequence. The least-squares optimum approach involves the computation of the three-dimensional (3-D) Fourier transform of the sequence, followed by the detection of one or more planes in this domain with high energy concentration. We present a more efficient algorithm, based on...