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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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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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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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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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Denoise EEG signal by using Daubechies function

I have an EEG signal and it contains eye blink artifacts, i read some references and know that can detect eye blink and remove them by using wavelet transform but i don't know that how do it, How to detect eye blink? Have any tutorials for me,…
saga
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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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Image enhancement in Wavelet Domain

Hi im trying to do mammogram image enhancement in wavelet domain based on this paper A Direct Image Contrast Enhancement Algorithm in the Wavelet Domain for Screening Mammograms. Where its used 4 level decomposition with 'db16' wavelet. The main…
Mario
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What are the possible parameters to wfuseimg in MATLAB?

The function wfuseimg fuses two images using wavelets. However, its documentation is quite poor (for MATLAB standards) and lacks general description. Particularly, on which options exist for each of the inputs. What are the possible inputs for…
Ander Biguri
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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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Can't convert dates in WaveletComp

First, here's the dput of my data: WaveletSite1Oxygen2 <- structure(list(Date = structure(c(741830400, 746668800, 749088000, 751507200, 753926400, 756345600, 759369600, 761788800, 764208000, 766627200, 770256000, 773366400, 778118400, 780537600,…
SecretBeach
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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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