Responses of Gabor wavelets in the mid-frequency space build a local spectral representation scheme with optimal properties regarding the time-frequency uncertainty principle. However, when using Gabor wavelets we observe a skewness in the mid-frequency space caused by the spreading effect of Gabor wavelets. Though in most current applications the skewness does not obstruct the sampling of the ...

In this paper a new optical channel drop filter (CDF) based on two dimensional (2-D) photonic crystals (PhC) with hexagonal shaped structure is proposed and numerically demonstrated by using the finite-difference-time-domain (FDTD) and plane-wave-expansion (PWE) techniques. Photonic crystals (PhCs) are artificial dielectric nanostructure materials in which a periodic modulation of the material ...

For signal-based design of orthonormal (ON) wavelets, an optimization of a cost function over an N -dimensional angle space is required. However: (1) the N -dim space includes both smooth and non-smooth wavelets; (2) many of the smooth wavelets are similar in shape. A more practical approach for some applications may be to construct a library of smooth ON wavelets in advance—a library that cons...

we propose a robust quantization-based image watermarking scheme, called the gradient direction watermarking (GDWM), and based on the uniform quantization of the direction of gradient vectors. In GDWM, the watermark bits are embedded by quantizing the angles of significant gradient vectors at multiple wavelet scales. The proposed scheme has the following advantages: 1) Increased invisibility of...

The goal of this paper is to introduce a complete analysis/resynthesis method for the stationary part of voiced-sounds. The method is based on a new class of wavelets, the Harmonic-Band Wavelets (HBWT). Wavelets have been widely employed in signal processing [1, 2]. In the context of sound processing they provided very interesting results in their first harmonic version: the Pitch Synchronous W...

We introduce a fast simple method for computing the real continuous wavelet transform (CWT). The approach achieves O N ( ) complexity per scale and the filter coefficients can be analytically obtained by a simple integration. Our method is to use P wavelets per octave and to approximate them with their oblique projection onto a space defined by a compact scaling function. The wavelet templates ...

In this work we review the parameterization of filter coefficients of compactly supported orthogonal wavelets used to implement the discrete wavelet transform. We also present the design of wavelet based filters as a constrained optimization problem where a genetic algorithm can be used to improve the compression ratio on gray scale images by minimizing their entropy and we develop a quasi-perf...

The work presents an implementation of discrete wavelet transform (DWT) using systolic array architecture in VLSI. The architecture consists of filter unit, storage unit and control unit. This performs calculations of low pass and high pass coefficients by using only one multiplier. This architecture has been implemented and simulated using VLSI. The hardware utilization efficiency is more as c...

We present biorthogonal and orthonormal wavelets for embedded zerotree wavelet compression of fingerprint images. By simulated annealing over the wavelet filter coefficients, using a composite cost function dependent upon a parameter k 2 which weights the relative importance of the wavelet's bandwidth and time dispersion, a series of wavelets is obtained. Each of these is optimal in terms of a ...