FFTInitAlloc

Allocates memory and fills in context data needed for the image FFT functions to operate.

Syntax

IppStatus ippiFFTInitAlloc_R_32s (IppiFFTSpec_R_32s** ppFFTSpec, int orderX, int orderY, int flag, IppHintAlgorithm hint);

IppStatus ippiFFTInitAlloc_R_32f (IppiFFTSpec_R_32f** ppFFTSpec, int orderX, int orderY, int flag, IppHintAlgorithm hint);

IppStatus ippiFFTInitAlloc_C_32fc (IppiFFTSpec_C_32fc** ppFFTSpec, int orderX, int orderY, int flag, IppHintAlgorithm hint);

Parameters

ppFFTSpec	Pointer to the pointer to the FFT context structure being initialized.
orderX, orderY	Order of the FFT in x- and y- directions, respectively.
flag	Flag to choose the results normalization option.
hint	Option to select the algorithmic implementation of the transform function (see Table “Hint Arguments for Linear Transform Functions”).

Description

The function ippiFFTInitAlloc is declared in the ippi.h file. This function allocates memory and initializes the context structure pFFTSpec needed to compute the forward and inverse FFT of a two-dimensional image data.

The ippiFFTFwd and ippiFFTInv functions called with the pointer to the initialized pFFTSpec structure as an argument will compute the fast Fourier transform with the following characteristics:

length N=2^orderX in x-direction by M=2 ^orderY in y-direction
results normalization mode as set by flag (see Table “Normalization Factors for Fourier Transform Results”)
computation algorithm indicated by hint.

Return Values

ippStsNoErr	Indicates no error. Any other value indicates an error or a warning.
ippStsNullPtrErr	Indicates an error condition if pFFTSpec pointer is `NULL`.
ippStsFftOrderErr	Indicates an error condition if the FFT order value is illegal.
ippStsFFTFlagErr	Indicates an error condition if flag has an illegal value.
ippStsMemAllocErr	Indicates an error condition if memory allocation fails.