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Questions tagged [wavelet-transform]

Use this tag to refer to the multi-scale signal representation by wavelets.

The wavelet transform is multi-scale representation of a signal by wavelets. The two most popular types of this transform are the continuous wavelet transform (with continuous time-scale plane) and the discrete wavelet transform (with dyadic dilation and position of the wavelets).

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Units of "widths" argument to scipy.signal.cwt() function

I am confused about the widths parameter that gets passed to scipy.signal.cwt() and by extension to scipy.signal.find_peaks_cwt(). A previous and very helpful Stack Overflow question (and pointers therein) explained away most of my confusion. The…
Curt F.
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How can DWT be used in LSB substitution steganography

In steganography, the least significant bit (LSB) substitution method embeds the secret bits in the place of bits from the cover medium, for example, image pixels. In some methods, the Discrete Wavelet Transform (DWT) of the image is taken and the…
Reti43
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How to denoise data using wavelet transform

I want to denoise the signal with wavelet transform, but somehow the data after denoising doesn't change significantly the code: df = pd.read_csv('0311LalaStand5Min1.csv', low_memory=False) columns = ['Fx','Fy','Fz','Mx','My','Mz'] selected_df =…
stack offer
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How to combine Wavelet Transform and Frequency Filtering

I need to implement the following de-noising on ECG signal: Discrete wavelet transform to 9 levels with 'db6' wavelet Filter the frequencies (not the details coefficients) on the 9-th level in the range 0-0.35Hz Reconstruct the signal using only…
Angelo
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Wavemulcor package - wave.multiple.cross.correlation function - replacement has length zero

I would like to use the wavemulcor package and in particular the wave.multiple.cross.correlation function to perform a wavelet multiple cross correlation on my data. I am following the example as per the package manual but using my data instead.…
TheGoat
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scipy.signal.cwt is getting a value error in correlate()

I'm getting a weird error when attempting to use scipy.signal.cwt: I have some list c, and I want to take the continuous wavelet transform like this: scipy.signal.cwt(np.array(c), scipy.signal.morlet, np.arange(.01,.1,.01)) and I get a weird…
Andrew Spott
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Continuous Wavelet Transform with Scipy.signal (Python): what is parameter “widths” in cwt() function? (time-frequency)

I search to draw a time-frequency signal with a discrete temporal signal (sampling step = 0.001sec). I use Python and the library Scipy.signal. I use the function cwt(data, wavelet, widths), which returns a matrix, to do a continuous wavelet…
ArnoNoo
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Continuous Wavelet Tranform- How to choose the scales

I have a signal coming from an accelerometer which has already been filtered in the band 0.5-15Hz. I would like to understand in particular how frequencies are distributed in two bands (0.5-3, 3-6) over time, so I thought about using CWT with morlet…
Gianluca Amprimo
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pywavelet signal reconstruction

I am trying to understand the concept of wavelets using the pywavelet library. My first step was to see how I could reconstruct a given input signal using the wavelet coefficients. Please see my code below: db1 = pywt.Wavelet('db1') cA6, cD6,cD5,…
user1274878
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Python package for maximal overlap discrete wavelet transform(MODWT)

I have to use python to reproduce results from a paper where MODWT is used. I'm currently using pywt and it only has stationary wavelet transform(SWT). I research a little bit and it seems there is currently no package for MODWT and I also find that…
TheStupidOne
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2D wavelet filtering in python on an image

I'm trying to do 2d wavelet filtering in python. I found out about PyWavelets and I have been messing around with it for awhile. I am trying to do the transformation for 4 levels. When I print it out it gives werid output and I'm not sure exactly…
Kasarrah
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How to Display wavelet transformation function dwt2 results in matlab

I am applying dwt2 function on an image to apply wavelet transformation which is giving four result images cA(low pass image),cH (Horizontal Detail image),cV(Vertical Detail Image),cD (Diagonal Detail Image). Every this fine till Now. I want to…
saimadhu.polamuri
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Wavelet reconstruction of time series

I'm trying to reconstruct the original time series from a Morlet's wavelet transform. I'm working in R, package Rwave, function cwt. The result of this function is a matrix of n*m (n=period, m=time) containing complex values. To reconstruct the…
user3369539
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Is this wavelet transform implementation correct?

I am searching for alternatives to the FFT to create a spectrogram analyser in python. I heard that the wavelet transform is faster and provides better time accuracy than the short time FFT. I went in this wikipedia article that features the Haar…
user2464424
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How to perform lowpass filtering in RGB images with Discrete Wavelet Transform in Python

I am trying to implement the following paper: https://link.springer.com/article/10.1007/s11042-011-0835-9 In this paper, the authors say the following: It seems that the authors filter the image with a lowpass DWT filter and then subtract the…
mad
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