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Questions tagged [dwt]

DWT stands for Discrete Wavelet Transform. This transformation is commonly used in signal processing. Its main advantage over Fourier transform is its ability to preserve temporal information.

DWT stands for Discrete Wavelet Transform. This transformation is commonly used in signal processing.
Wavelets are considered as more advanced tool than Fourier transform for signal processing. DWT's main advantage is its ability to preserve temporal information of the signal while introducing frequency properties. This advantage is achieved due to the use of compact basis functions - the wavelets. The compact basis functions integrates spectral (frequency) information over compact domain thus preserving temporal information.

There are many types of DWT differes by their construction of their basis function. Very useful DWTs are Haar wavelets and Gabor wavelets.

For more information see wikipedia.

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how to import the pywt library which is a python library in dev c ++?

I'm trying to run this code which was picked up by someone I can't reach anymore, the code calculates the dwt2 and idwt2 of a square matrix #include #include #include using namespace std; int main() { int…
RoseDevStack
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Difference between MODWT (Maximum Overlap Discrete Wavelet Transform) and WAVEDEC/DFT (Discrete Wavelet Trasnform) in MATLAB

I need to perform the Discrete Wavelet Transform of a discrete signal in MATLAB. What is the difference between the commands MODWT and WAVEDEC? I see that MODWT operates the Maximum Overlapped Discrete Wavelet Transform (MODWT), whereas Wavedec…
EmThorns
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How to find the frequency bands of DWT signal transformation?

I am newbie in Signal Processing, I want find out the frequency rang each of level outputted by a Daubechies wavelet 'db4' transformation. The transformation is done with PyWavelets. I'm working in python and the code below outputs 5 detail levels…
Zizi96
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How does one perform DWT using R Studio?

Hello new to R Studio and having challenges in decomposing data using DWT to a daubechies series of 4 (db4) and n.levels = 4 to a data set of 72 varaiables and 1 observation(Depth(m)) Encountering an error Depth <- dwt(up.sample(Data[, c("DEPTH…
Edu Kin
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Why does salt & pepper noise=0 change the image?

I have an RGB image 512x512, and a 64x64 Watermark image which embedded with DWT, SVD. watermarked image is 512x512 and double. extracted image is good (bit error rate=0). But when I use imnoise with d=0, the extracted image is not good and…
Marzi.KP
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how to measure shift variance in discrete Wavelet transform (DWT) and complex wavelet transform

I have a EEG data of epileptic patients. I have applied two different approaches for feature generation i.e Discrete Wavelet Transform (DWT) and Dual Tree Complex Wavelet Tranform(DTCWT). I have found better results with DTCWT. To support my…
anonymous
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Relation of Sampling frequency, Signal length (datapoints) and Time range of Discrete Wavelet Transform?

As above lets Fs is sampling frequency, L is signal's length and t is time range. As using mdwtdec in Matlab in order to decompose multi-raw signal into specific frequency band, I just notice that decomposed signal's length at 1st level is split…
Q.H.Chu
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Why does the inverse wavelet convert images to a negative range?

Ok my work is divided in three parts: I applied wavelet transform on an Image I changed (enhanced) the LL area I applied Inverse wavelet transform I've expected to get an enhanced image but in part 3 when I applied it the range of image went to…
A.omrani
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Discrete Wavelet Transform (DWT) - Down sampling of the original signal by 2

I am working with DWT2 on matlab for a 2D matrix of time series data. When I perform dwt2 on the matrix, it returns the follwing four values : [ca,ch, cv, cd] = dwt2(mat,'db4','mode', 'per') I read about what these four values CA, CH, CV and CD…
Piyush Doke
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Using waveletstudio library

Please i hope that someone here already used waveletStudio library. I have a problem : when i pass an Array with more than 9.000.000 of samples, program exit with An unhandled exception of type 'System.OutOfMemoryException' occurred in…
gggkg
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discrete wavelet transform and inverse discrete wavelet transform TypeError in python

I am currently doing a project in image processing. I am new to python. Any help will be appreciated. I am decomposing image into bands using discrete wavelet transform and modify the coefficients. So below code gives me an error. here is the…
Shaan
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Discrete wavelet transform in R on Big data

I'm doing a discrete wavelet transform using the following code in R. My data in data.table format is fetched from a hive table in chunks and converted into a matrix and then the wavelet transform is applied as below.…
ML_Passion
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Multilevel Wavelet Decomposition not working

I am trying to decompose the given wave by using a db4 wavelet and 5 level decomposition. Here is the code for the same : coeffs = pywt.wavedec(yourResultA,'db4',level = 5) However the editor is giving me the following error: Level value of 5 is…
Rohan Akut
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running Discrete wavelet transform in R Language

Please can someone help with a solution for running Discrete wavelet transform in R. I have tried with the following data format; Year, Rain. Year is in form of 1970,1972,1973.... and Rain in form of 200, 85, 34, 56 23, 0.5... etc. I don't know if…
Amobi Amanambu
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SyntaxError: can't assign to function call-Python

I am getting "SyntaxError: can't assign to function call" for a code on DWT on a signal from a text file. I appreciate if anyone can explain why is this syntax error. import numpy as np import pywt import array array.array('i') k =…
Dattaprasad
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