dyadup

Dyadic upsampling

Syntax

Y = dyadup(X)

Y = dyadup(X,EVENODD)

Y = dyadup(___,'type')

Description

Y = dyadup(X) upsamples odd-indexed elements of X. Y contains odd-index samples of X in this case. Specify X as a vector or matrix. When you specify X as a vector, the function returns an extended copy of vector X upsampled by inserting zeros.

Y = dyadup(X,EVENODD), where X upsamples even- or odd-indexed elements of X. Y can contain even- or odd-indexed samples of X depends on the value of EVENODD. Specify X as a vector. When you specify X as a vector, the function returns an extended copy of vector X obtained by inserting zeros.

dyadup implements a simple zero-padding scheme very useful in the wavelet reconstruction algorithm.

Y = dyadup(___,'type') returns a extended copies of X obtained by inserting columns or rows, or rows and columns of X using 'type' argument. Specify X as a matrix.

Examples

Perform Dyadic Upsampling

Create a vector of data that you want to upsample.

s = 1:5 

s = 1×5

     1     2     3     4     5

Upsample elements at odd indices.

dse = dyadup(s) 

dse = 1×11

     0     1     0     2     0     3     0     4     0     5     0

You can also upsample the elements in X1 by setting EVENODD to 1.

dse1 = dyadup(s,1)

dse1 = 1×11

     0     1     0     2     0     3     0     4     0     5     0

Upsample elements at even indices.

dso = dyadup(s,0) 

dso = 1×9

     1     0     2     0     3     0     4     0     5

Create a matrix data that you want to upsample.

s = (1:2)'*(1:3)

s = 2×3

     1     2     3
     2     4     6

Upsample rows at even indices.

der = dyadup(s,1,'r') 

der = 5×3

     0     0     0
     1     2     3
     0     0     0
     2     4     6
     0     0     0

Upsample columns at odd indices.

doc = dyadup(s,0,'c')  

doc = 2×5

     1     0     2     0     3
     2     0     4     0     6

Upsample rows and columns at even indices.

dem = dyadup(s,1,'m')

dem = 5×7

     0     0     0     0     0     0     0
     0     1     0     2     0     3     0
     0     0     0     0     0     0     0
     0     2     0     4     0     6     0
     0     0     0     0     0     0     0

Using default values for dyadup and dyaddown, we have: dyaddown(dyadup(s)) = s.

s = 1:5

s = 1×5

     1     2     3     4     5

uds = dyaddown(dyadup(s))

uds = 1×5

     1     2     3     4     5

In general reversed identity is false.

Input Arguments

X — Data to be upsampled

vector | matrix

Data to be upsampled, specified as a vector or matrix. X is a vector when you do not use the 'type' argument in the dyadup function and X is a matrix when you use the 'type' argument in the dyadup function.

EVENODD — Even- or odd-indexed samples of X

1 (default) | positive integer

Even- or odd-indexed samples of X, specified as a positive integer.

Y contains the even- or odd-indexed samples of X depends on the value of EVENODD:

• If EVENODD is even, then Y(2k–1) = X(k), Y(2k) = 0.

• If EVENODD is odd, then Y(2k–1) = 0, Y(2k) = X(k).

dyadup defaults to EVENODD = 1 (zeros in odd-indexed positions).

'type' — Type of upsampling

'c' (default) | 'r' | 'm'

Type of upsampling , specified as one of the following:

• 'c' to upsample columns of X

• 'r' to upsample rows of X

• 'm' to upsample rows and columns of X

Output Arguments

Y — Dyadic upsampled version of X

vector | matrix

Dyadic upsampled version of X, returned as a vector or a matrix.

References

[1] Strang, Gilbert, and Truong Nguyen. Wavelets and Filter Banks. Rev. ed. Wellesley, Mass: Wellesley-Cambridge Press, 1997.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• If X is empty, generated code returns X and MATLAB^® returns [].

• Suppose that all of the following conditions are true:

  • X is a variable-size array.

  • X is not a variable-length column vector (:-by-1).

  • X is a column vector at run time.

  • 'type' is not supplied.

  In generated code, the output for y = dyadup(X,k), where k is optional, matches the output for y = dyadup(X,k,'c'). In MATLAB, the output for y = dyadup(X,k) matches the output for y = dyadup(X,k,'r').

  For code generation, when you do not specify 'type', if you want dyadup to treat X as a column vector, X must be a variable-length vector (:-by-1).

GPU Arrays

Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

The dyadup function fully supports GPU arrays. To run the function on a GPU, specify the input data as a gpuArray (Parallel Computing Toolbox). For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).

Version History

Introduced before R2006a