Intel® Integrated Performance Primitives (Intel® IPP) Developer Guide and Reference

ID 790148
Date 3/22/2024
Public
Document Table of Contents

WTFwdInit

Initializes the forward wavelet transform context structure.

Syntax

IppStatus ippiWTFwdInit_32f_C1R(IppiWTFwdSpec_32f_C1R* pSpec, const Ipp32f* pTapsLow, int lenLow, int anchorLow, const Ipp32f* pTapsHigh, int lenHigh, int anchorHigh);

IppStatus ippiWTFwdInit_32f_C3R(IppiWTFwdSpec_32f_C3R* pSpec, const Ipp32f* pTapsLow, int lenLow, int anchorLow, const Ipp32f* pTapsHigh, int lenHigh, int anchorHigh);

Include Files

ippi.h

Domain Dependencies

Headers: ippcore.h, ippvm.h, ipps.h

Libraries: ippcore.lib, ippvm.lib, ipps.lib

Parameters

pSpec
Double pointer to the forward wavelet transform specification structure.
pTapsLow
Pointer to lowpass filter taps.
lenLow
Length of the lowpass filter.
anchorLow
Anchor position of the lowpass filter.
pTapsHigh
Pointer to highpass filter taps.
lenHigh
Length of the highpass filter.
anchorHigh
Anchor position of the highpass filter.

Description

This function initializes the specification structure pSpec for a one-level wavelet decomposition.

The forward wavelet transform specification structure contains parameters of a wavelet filter bank used for image decomposition. The filter bank consists of two analysis filters and includes the lowpass decomposition filter (or coarse filter) and the highpass decomposition filter (or detail filter).

The parameters pTapsLow and pTapsHigh specify coefficients, and anchorLow and anchorHigh - anchor positions for two synthesis filters. The anchor value sets the initial leftmost filter position relative to image row or column as shown in the figure below:

Anchor Value and Initial Filter Position for Wavelet Decomposition

Here a stands for anchor value, N is filter length, x0 is the starting pixel of the processed row or column, and x-1, x-2 ,... are the additional border pixels that are needed for calculations. The anchor value and filter length completely determine right, left, top, and bottom border sizes for the source image used in decomposition. The corresponding C-language expressions to calculate border sizes are given in the description of ippiWTFwd function.

For an example on how to use this function, refer to the example provided with the ippiWTInv function description.

Return Values

ippStsNoErr

Indicates no error. Any other value indicates an error or a warning.

ippStsNullPtrErr

Indicates an error when any of the specified pointers is NULL.

ippStsNumChannelsErr

Indicates an error when numChannels has an illegal value.

ippStsSizeErr

Indicates an error when filter length lenLow or lenHigh is less than 2.

ippStsAnchorErr

Indicates an error when anchor position anchorLow or anchorHigh is less than zero.

See Also