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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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Wavelet transform in openCV

did someone tried to implement DWT in opencv or in C++? I saw older posts on this subject and i didn't find them useful for me, because I need a approximation coefficient and details as a result of wavelet transformation. I tried to add this to my…
la lluvia
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How to Combine pyWavelet and openCV for image processing?

I need to do an image processing in python. i want to use wavelet transform as the filterbank. Can anyone suggest me which one library should i use? I had pywavelet installed, but i don't know how to combine it with opencv. If i use wavedec2…
rizkie
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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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Looping and TemplateRepeatIndex in Dreamweaver template

I am having some trouble with accessing variables, here in this case Setvariable. When I go inside loop, variable doesn't exists. Anyone have any insight on this. Appreciate your help Below is my code section in template. Would you please help when…
krishnakumar k
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How to calculate energy of an image using Python?

I am trying to calculate the energy of an image. I want to use python. I got one solution from the website but there is a little bit confusing the person who posted the question is telling output of his program is the wrong to compare to Matlab. I…
raviraj
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Discrete Wavelet Transform integer Daub 5/3 lifting issue

I'm trying to run an integer-to-integer lifting 5/3 on an image of lena. I've been following the paper "A low-power Low-memory system for wavelet-based image compression" by Walker, Nguyen, and Chen (Link active as of 7 Oct 2015). I'm running into…
Goz
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Hijri (Persian calendar) For DwtCalendar.js

This is a DHTML Gregorian calendar widget. I'm trying to make an Hijri (Persian Calendar - Jalali) widget. Does anyone have any ideas?
bizzr3
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how to denormalize image in python?

I am working on a project where i have to first normalize the image to [0,1] and then perform dwt and idwt on the image after the processing. so first i convert the image to an array then i normalize it with this code def normalization (array): …
Z98n
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Applying Haar Wavelet transform to time series data

I am trying to apply a Haar wavelet transform to stock market data for noise reduction, before feeding the data to a RNN (LSTM). As this data is in 1D, I'm using a single level DWT as follows: import pywt x = [3, 7, 1, 1, -2, 5, 4, 6,…
Adeel Hashmi
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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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Dump Tridion Component as XML

What is the simplest way of dumping Tridion component content (based on a given schema, i.e.: non-arbitrary) into XML using modular template? Specifically, need to pass component's content to/as ASP.Net custom control, that is, something…
esteewhy
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Argument for PHP vs. DWT

I was having a "discussion" with my manager today about the merits of using PHP includes and functions as a template to build websites more quickly and efficiently. He has been using Dreamweaver templates for years and sees it as really the best way…
DesignUtensil
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Discrete Wavelet Transform on images and watermark embedding in LL band coefficients, data is lost when IDWT-DWT is performed again?

I'm writing an image watermarking system to hide a watermark in an image's low frequency band by transforming the image's luminance channel with a Discrete Wavelet Transform, then modifying coefficients in the LL band of the DWT output. I then do an…
Patrick
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How to reconstruct image from a percentage of largest DWT coefficients in Matlab

I want to reconstruct an image from a multi-level DWT transform from only 5% of the largest coefficients while setting the rest to zero. I'm not sure which coefficients I need to choose the largest 5% from? A, H, V, or D? Here is what I've done so…
DML2014
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Discrete Wavelet Transform Matlab

I am trying to use the functions provided in the Matlab Wavelet Toolbox to create a multi-level discrete wavelet decomposition of an image, extracting the coefficients, manipulating them, and recomposing them back into the image. I tried using a…
bonapart3
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