WOLFRAM

applies the function f to the arrays of coefficients and indices of a ContinuousWaveletData or DiscreteWaveletData object.

WaveletMapIndexed[f,dwd,wind]

applies f to the DiscreteWaveletData coefficients specified by wind.

WaveletMapIndexed[f,cwd,octvoc]

applies f to the ContinuousWaveletData coefficients specified by octvoc.

Details

Examples

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Basic Examples  (2)Summary of the most common use cases

Rescale all coefficients of a discrete wavelet transform by 20:

Out[2]=2

Normal gives the array of coefficients:

Out[3]=3

Compare with the unmodified coefficients:

Out[4]=4

Amplify the {1} coefficient of the stationary wavelet transform of an image:

Out[1]=1
Out[2]=2

The inverse wavelet transform gives an image with vertical edges sharpened:

Out[3]=3

Scope  (11)Survey of the scope of standard use cases

Basic Uses  (3)

Apply an arbitrary function to all coefficients of a discrete wavelet transform:

Out[1]=1

Apply a symbolic function that also depends on the wavelet index for each coefficient vector:

Out[1]=1

WaveletMapIndexed operates on ContinuousWaveletData or DiscreteWaveletData:

Out[1]=1

The result is a wavelet data object of the same type:

Out[2]=2

The modified data can be used in other wavelet functions such as inverse wavelet transforms:

Out[3]=3

Coefficient Specification  (4)

Transform only specified coefficients in DiscreteWaveletData:

Out[1]=1

Apply a function to detail coefficients only, using the index pattern {___, 1}:

Out[2]=2

Apply a function to coarse coefficients only, using the index pattern {___, 0}:

Out[3]=3

Transform only specified coefficients in a ContinuousWaveletData:

Out[1]=1

Apply a function to coefficients in the first octave {1,_} only:

Out[2]=2

Apply a function to all coefficients except those in the second octave, first voice {2,1}:

Out[3]=3

The function f can depend on the wavelet index as its second argument:

Out[1]=1

Define a function with an arbitrary dependence on the wavelet index:

Apply the function to continuous wavelet transform coefficients:

Out[2]=2

Data  (4)

For list data, the coefficients supplied as the first argument of f are lists:

Out[2]=2

Apply a function that transforms lists:

Out[3]=3

For multidimensional data, the coefficients are arrays of the same depth:

Out[2]=2

Apply a function that transforms array coefficients of that depth:

Out[3]=3

For image data, the coefficients are supplied to f as Image objects:

Out[2]=2

The coefficients have the same number of channels as the original image:

Out[3]=3

Apply a function that transforms image coefficients:

Out[4]=4
Out[5]=5

For sound data, the coefficients are two-dimensional arrays:

Out[1]=1

Dimensions of one coefficient:

Out[2]=2

The two dimensions specify the channel number and the wavelet coefficients for that channel:

Out[3]=3

Apply a function that transforms two-channel data:

Out[5]=5
Out[6]=6

Reconstructed Sound data:

Out[7]=7

Applications  (7)Sample problems that can be solved with this function

Data Processing  (2)

Coefficients with short indices correspond to small-scale structure in the data:

Zero all small-scale coefficients from the stationary wavelet transform of random data:

Out[2]=2

The inverse wavelet transform varies only on larger scales:

Out[3]=3

Perform a simple thresholding operation by removing low-amplitude wavelet coefficients:

Out[2]=2

Compare with the original data:

Out[3]=3

Image Processing  (3)

Blur an image by setting small-scale detail coefficients to zero:

Out[1]=1

Compare with the original image:

Out[2]=2

Sharpen an image by amplifying small-scale detail coefficients:

Out[1]=1

Compare with the original image:

Out[2]=2

Use a mask image to vary between blurring and sharpening across an image:

Out[1]=1

Compare with the original image:

Out[2]=2

Sound Processing  (1)

Apply a nonlinear function to wavelet coefficients for sound data:

Out[2]=2

Inverse transform to obtain a reconstructed sound object:

Out[3]=3

Wavelet Thresholding  (1)

Perform a wavelet-based shrinkage based on conditional mean:

Out[3]=3

Compute a discrete wavelet transform up to refinement level 6:

Compute the standard deviation for the finest detail coefficients:

Out[5]=5

Compute the standard deviation for all wavelet coefficients:

Out[6]=6

Assuming a Gaussian mixture model, variance can be estimated in the proportion to :

Shrinkage estimates of the signal coefficients are given by:

Use WaveletMapIndexed to map over detail coefficients:

Reconstruct thresholded signal coefficients:

Out[13]=13

Properties & Relations  (3)Properties of the function, and connections to other functions

MapIndexed[f,expr] applies f to the parts of any expression:

Out[1]=1

WaveletMapIndexed[f,wd] applies f to the coefficients in the wavelet data object wd:

Out[3]=3

WaveletMapIndexed[vMap[f,v],wd] applies f to each part of each coefficient:

Out[4]=4

MapIndexed gives the part specification as the second argument of f:

Out[1]=1

WaveletMapIndexed gives the wavelet index specification as the second argument of f:

Out[2]=2

WaveletMapIndexed transforms arrays of coefficients, giving a new DiscreteWaveletData:

Out[2]=2

Use Map and Normal[dwd] to transform coefficients into normal expressions:

Out[3]=3

Or use ReplaceAll (/.):

Out[4]=4

Possible Issues  (2)Common pitfalls and unexpected behavior

The function f is always passed the index specification as its second argument:

Out[2]=2

Use a function that operates on its first argument only:

Out[3]=3

The function f should return an array or image of the same dimensions:

Out[2]=2

Listable functions return an array of the same dimensions:

Out[3]=3

Arithmetic operations such as multiplication are Listable:

Out[4]=4

Use Map for functions that are not Listable:

Out[5]=5
Wolfram Research (2010), WaveletMapIndexed, Wolfram Language function, https://reference.wolfram.com/language/ref/WaveletMapIndexed.html.
Wolfram Research (2010), WaveletMapIndexed, Wolfram Language function, https://reference.wolfram.com/language/ref/WaveletMapIndexed.html.

Text

Wolfram Research (2010), WaveletMapIndexed, Wolfram Language function, https://reference.wolfram.com/language/ref/WaveletMapIndexed.html.

Wolfram Research (2010), WaveletMapIndexed, Wolfram Language function, https://reference.wolfram.com/language/ref/WaveletMapIndexed.html.

CMS

Wolfram Language. 2010. "WaveletMapIndexed." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/WaveletMapIndexed.html.

Wolfram Language. 2010. "WaveletMapIndexed." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/WaveletMapIndexed.html.

APA

Wolfram Language. (2010). WaveletMapIndexed. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/WaveletMapIndexed.html

Wolfram Language. (2010). WaveletMapIndexed. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/WaveletMapIndexed.html

BibTeX

@misc{reference.wolfram_2025_waveletmapindexed, author="Wolfram Research", title="{WaveletMapIndexed}", year="2010", howpublished="\url{https://reference.wolfram.com/language/ref/WaveletMapIndexed.html}", note=[Accessed: 28-March-2025 ]}

@misc{reference.wolfram_2025_waveletmapindexed, author="Wolfram Research", title="{WaveletMapIndexed}", year="2010", howpublished="\url{https://reference.wolfram.com/language/ref/WaveletMapIndexed.html}", note=[Accessed: 28-March-2025 ]}

BibLaTeX

@online{reference.wolfram_2025_waveletmapindexed, organization={Wolfram Research}, title={WaveletMapIndexed}, year={2010}, url={https://reference.wolfram.com/language/ref/WaveletMapIndexed.html}, note=[Accessed: 28-March-2025 ]}

@online{reference.wolfram_2025_waveletmapindexed, organization={Wolfram Research}, title={WaveletMapIndexed}, year={2010}, url={https://reference.wolfram.com/language/ref/WaveletMapIndexed.html}, note=[Accessed: 28-March-2025 ]}