Wavelet Analysis Essay

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The development of wavelets can be linked to several separate trains of thought, starting with Haar's work in the early 20th century. The wavelets are functions that satisfy certain mathematical requirements and are used in on behalf of data or other functions. Wavelet is a waveform of effectively limited time that has an average value of zero. This wave in itself refers to the situation that this function is oscillatory. And Wavelet analysis technique has the ability to perform local analysis. It can analyze a localized area of a larger signal. Wavelet analysis is capable of revealing aspects of data that other signal analysis methods miss aspects like trends, breakdown points, self-similarity, and discontinuities in higher derivatives. Wavelet …show more content…

In similarly, with wavelet analysis, the scale is related to the frequency of the signal. The sifting a wavelet simply means delaying its onset. Mathematically, delaying a function by k is represented by : Fig: 4.0.3Shifting in wavelets 4.4 Multi Resolution Analysis in WT MULTI-RESOLUTION ANALYSIS analyzes the signal at different frequencies among different resolutions. However every spectral component is not resolved equally as was the case in the STFT. In MRA gives good time resolution and poor frequency resolution at high frequencies and good frequency resolution and poor time resolution at low frequencies process. This approach is helpful when the signal at hand has high frequency material for short durations and low frequency components for long time. 4.5 Wavelet Properties Various properties of wavelet transforms (WT) is described by followed: In Regularity The window for a function is the smallest space-set outside which function is identically zero. In order of the polynomial that can be approximated is determined through number of vanishing moments of wavelets and is useful for compression …show more content…

This implies that the mean square error (MSE) introduced during the quantization of the Discrete wavelet transform (DWT) coefficients is equal to the MSE in the reconstructed signal. This is desirable since it implies that the quantized can be considered in the transform domain to take advantage of the wavelet decomposition structure. The synthesis filters are transposes of analysis filters. However, in the case of 44 45 biorthogonal wavelets, the basic functions are not orthogonal and thus not energy preserving. Hence, we use the orthogonality parameter to measure the wavelet's deviation from orthogonality. It is given by: (4.2) Filter length: in shorter synthesis basis functions are desired for minimize deformation that affects the subjective quality of the image. The longer filters are responsible for ringing noise in the reconstructed image at low bit rates. The Vanishing order is a measure of the compaction property of the wavelets. The synthesis wavelet is said to have p vanishing moments. In the case of orthogonal wavelets, the analysis wavelet function is same as the combination wavelet function. For biorthogonal wavelets, the analysis wavelet function is different from the synthesis wavelet

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