Allocates memory and initializes the forward wavelet transform context structure.
Syntax
IppStatus ippiWTFwdInitAlloc_32f_C1R(IppiWTFwdSpec_32f_C1R** ppSpec, const Ipp32f* pTapsLow, int lenLow, int anchorLow, const Ipp32f* pTapsHigh, int lenHigh, int anchorHigh);
IppStatus ippiWTFwdInitAlloc_32f_C3R(IppiWTFwdSpec_32f_C3R** ppSpec, const Ipp32f* pTapsLow, int lenLow, int anchorLow, const Ipp32f* pTapsHigh, int lenHigh, int anchorHigh);
Parameters
- ppSpec
- Double pointer to the forward DWT context 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
The function ippiWTFwdInitAlloc is declared in the ippi.h file. This function allocates memory for the context structure pSpec of a one-level wavelet decomposition and initializes this structure.
The forward wavelet transform context 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 “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.
Once allocated and initialized the context structure can be used in several threads of calculations as well as in a number of wavelet decomposition levels.
Example “Using Intel IPP Functions for Wavelet Transforms” shows how to use the function ippiWTFwdInitAlloc_32f_C1R.
Return Values
ippStsNoErr |
Indicates no error. Any other value indicates an error or a warning. |
ippStsNullPtrErr |
Indicates an error condition if pTapsLow, pTapsHigh, or pSpec pointer is NULL. |
ippStsSizeErr |
Indicates an error condition if filter length lenLow or lenHigh is less then 2. |
ippStsAnchorErr |
Indicates an error condition if anchor position anchorLow or anchorHigh is less then zero. |
ippStsMemAllocErr |
Indicates an error condition in case of memory allocation failure for the context structure. |