FFTInv
Applies an inverse FFT to complex source data and stores results in a destination image.
Syntax
Case
1
: Not-in-place operation on floating-point data
IppStatus ippiFFTInv_PackToR_<mod>(const Ipp32f*
pSrc
, int
srcStep
, Ipp32f*
pDst
, int
dstStep
, const IppiFFTSpec_R_32f*
pFFTSpec
, Ipp8u*
pBuffer
);
Supported values for
mod
:
32f_C1R |
32f_C3R |
32f_C4R |
32f_AC4R |
Case
2
: Not-in-place operation on complex data
IppStatus ippiFFTInv_CToC_32fc_C1R(const Ipp32fc*
pSrc
, int
srcStep
, Ipp32fc*
pDst
, int
dstStep
, const IppiFFTSpec_C_32fc*
pFFTSpec
, Ipp8u*
pBuffer
);
Case
3
: In-place operation on floating-point data
IppStatus ippiFFTInv_PackToR_<mod>(Ipp32f*
pSrcDst
, int
srcDstStep
, const IppiFFTSpec_R_32f*
pFFTSpec
, Ipp8u*
pBuffer
);
Supported values for
mod
:
32f_C1IR |
32f_C3IR |
32f_C4IR |
32f_AC4IR |
Case
4
: In-place operation on complex data
IppStatus ippiFFTInv_CToC_32fc_C1IR(Ipp32fc*
pSrcDst
, int
srcDstStep
, const IppiFFTSpec_C_32fc*
pFFTSpec
, Ipp8u*
pBuffer
);
Include Files
ippi.h
Domain Dependencies
Headers:
ippcore.h
,
ippvm.h
,
ipps.h
Libraries:
ippcore.lib
,
ippvm.lib
,
ipps.lib
Parameters
- pSrc
- Pointer to the source image ROI.
- srcStep
- Distance in bytes between starts of consecutive lines in the source image.
- pDst
- Pointer to the destination image ROI.
- dstStep
- Distance in bytes between starts of consecutive lines in the destination image.
- pSrcDst
- Pointer to the source and destination image ROI for the in-place operation.
- srcDstStep
- Distance in bytes between starts of consecutive lines in the source and destination image for the in-place operation.
- pFFTSpec
- Pointer to the previously initialized FFT context structure.
- pBuffer
- Pointer to the external work buffer.
Description
This function operates with ROI.
This function performs an inverse FFT on each channel of the source image
pSrc
(
pSrcDst
for in-place flavors) and writes the restored image data into the corresponding channel of the destination image buffer
pDst
(
pSrcDst
for in-place flavors). The size of ROI is
N
x
M
, it is specified by the parameters
orderX
,
orderY
.
For the
ippiFFTInv_PackToR,
function flavor, the input buffer must contain data in
RCPack2D format
.
Before using the inverse FFT functions, you need to compute the size of the work buffer by
ippiFFTGetSize
and initialize the context structure by the
ippiFFTInit
function. The inverse FFT functions use the
pFFTSpec
context structure to set the mode of calculations and retrieve support data.
Return Values
- ippStsNoErr
- Indicates no error. Any other value indicates an error or a warning.
- ippStsNullPtrErr
- Indicates an error condition ifpSrc, pDst,orpFFTSpecpointer isNULL.
- ippStsStepErr
- Indicates an error condition ifsrcStepordstStepvalue is zero or negative.
- ippStsContextMatchErr
- Indicates an error condition if a pointer to an invalidpFFTSpecstructure is passed.
- ippStsMemAllocErr
- Indicates an error condition if memory allocation fails.
Example
FFTInv_CToC
:/******************************************************************************* * Copyright 2015-2020 Intel Corporation. * * This software and the related documents are Intel copyrighted materials, and * your use of them is governed by the express license under which they were * provided to you (License). Unless the License provides otherwise, you may not * use, modify, copy, publish, distribute, disclose or transmit this software or * the related documents without Intel's prior written permission. * * This software and the related documents are provided as is, with no express * or implied warranties, other than those that are expressly stated in the * License. *******************************************************************************/ // A simple example of performing the forward FFT for processing complex data. // implemented with Intel(R) Integrated Primitives (Intel(R) IPP) functions: // ippiFFTGetSize_C_32fc // ippiFFTInit_C_32fc // ippiFFTFwd_CToC_32fc_C1R // ippiFFTInv_CToC_32fc_C1R #include <stdio.h> #include "ipp.h" /* Next two defines are created to simplify code reading and understanding */ #define EXIT_MAIN exitLine: /* Label for Exit */ #define check_sts(st) if((st) != ippStsNoErr) goto exitLine; /* Go to Exit if Intel(R) IPP function returned status different from ippStsNoErr */ /* Results of ippMalloc() are not validated because Intel(R) IPP functions perform bad arguments check and will return an appropriate status */ int main(void) { IppStatus status; IppiFFTSpec_C_32fc *pSpec = NULL; /* Pointer to FFT spec structure */ /* Pointers to source/destination images */ Ipp32fc pSrcFwd[64] = {0}, pDstFwd[64] = {0}; Ipp32fc pSrcInv[64] = {0}, pDstInv[64] = {0}; Ipp32fc m3 = {-3, 0}, one = {1, 0}; Ipp8u *pMemInit = NULL, *pBuffer = NULL; /* Pointer to the work buffers */ int sizeSpec = 0, sizeInit = 0, sizeBuf = 0; /* size of FFT spec structure, Init and work buffers */ pSrcFwd[0] = m3; pSrcFwd[9] = one; check_sts( status = ippiFFTGetSize_C_32fc( 3, 3, IPP_FFT_DIV_INV_BY_N, ippAlgHintAccurate, &sizeSpec, &sizeInit, &sizeBuf ) ) /* memory allocation */ pSpec = (IppiFFTSpec_C_32fc*) ippMalloc( sizeSpec ); pBuffer = (Ipp8u*) ippMalloc( sizeBuf ); pMemInit = (Ipp8u*) ippMalloc( sizeInit ); check_sts( status = ippiFFTInit_C_32fc( 3, 3, IPP_FFT_DIV_INV_BY_N, ippAlgHintAccurate, pSpec, pMemInit ) ) /* forward FFT transform */ check_sts( status = ippiFFTFwd_CToC_32fc_C1R( pSrcFwd, 8*sizeof(Ipp32fc), pDstFwd, 8*sizeof(Ipp32fc), pSpec, pBuffer ) ) check_sts( status = ippsCopy_32fc( pDstFwd, pSrcInv, 64 ) ) /* inverse FFT transform */ check_sts( status = ippiFFTInv_CToC_32fc_C1R( pSrcInv, 8*sizeof(Ipp32fc), pDstInv, 8*sizeof(Ipp32fc), pSpec, pBuffer ) ) EXIT_MAIN ippFree( pMemInit ); ippFree( pSpec ); ippFree( pBuffer ); printf("Exit status %d (%s)\n", (int)status, ippGetStatusString(status)); return (int)status; }
FFTInv_RToPack
:/******************************************************************************* * Copyright 2015-2020 Intel Corporation. * * This software and the related documents are Intel copyrighted materials, and * your use of them is governed by the express license under which they were * provided to you (License). Unless the License provides otherwise, you may not * use, modify, copy, publish, distribute, disclose or transmit this software or * the related documents without Intel's prior written permission. * * This software and the related documents are provided as is, with no express * or implied warranties, other than those that are expressly stated in the * License. *******************************************************************************/ // A simple example of performing the inverse FFT for processing real data. // implemented with Intel(R) Integrated Primitives (Intel(R) IPP) functions: // ippiFFTGetSize_R_32f // ippiFFTInit_R_32f // ippiFFTFwd_RToPack_32f_C1R // ippiFFTInv_PackToR_32f_C1R #include <stdio.h> #include "ipp.h" /* Next two defines are created to simplify code reading and understanding */ #define EXIT_MAIN exitLine: /* Label for Exit */ #define check_sts(st) if((st) != ippStsNoErr) goto exitLine; /* Go to Exit if Intel(R) IPP function returned status different from ippStsNoErr */ /* Results of ippMalloc() are not validated because Intel(R) IPP functions perform bad arguments check and will return an appropriate status */ int main(void) { IppStatus status; IppiFFTSpec_R_32f *pSpec = NULL; /* Pointer to FFT spec structure */ /* Pointers to source/destination images */ Ipp32f pSrcFwd[64] = {0}, pDstFwd[64] = {0}; Ipp32f pSrcInv[64] = {0}, pDstInv[64] = {0}; /* Pointer to the work buffers */ Ipp8u *pMemInit = NULL; Ipp8u *pBuffer = NULL; int sizeSpec = 0, sizeInit = 0, sizeBuf = 0; /* size of FFT spec structure, Init and work buffers */ pSrcFwd[0] = -3; pSrcFwd[9] = 1; check_sts( status = ippiFFTGetSize_R_32f(3, 3, IPP_FFT_DIV_INV_BY_N, ippAlgHintAccurate, &sizeSpec, &sizeInit, &sizeBuf) ) /* memory allocation */ pSpec = (IppiFFTSpec_R_32f*) ippMalloc( sizeSpec ); pBuffer = (Ipp8u*) ippMalloc( sizeBuf ); pMemInit = (Ipp8u*) ippMalloc( sizeInit ); check_sts( status = ippiFFTInit_R_32f(3, 3, IPP_FFT_DIV_INV_BY_N, ippAlgHintAccurate, pSpec, pMemInit) ) /* forward FFT transform */ check_sts( status = ippiFFTFwd_RToPack_32f_C1R( pSrcFwd, 8*sizeof(Ipp32f), pDstFwd, 8*sizeof(Ipp32f), pSpec, pBuffer ) ) check_sts( status = ippsCopy_32f(pDstFwd, pSrcInv, 64) ) /* inverse FFT transform */ check_sts( status = ippiFFTInv_PackToR_32f_C1R( pSrcInv, 8*sizeof(Ipp32f), pDstInv, 8*sizeof(Ipp32f), pSpec, pBuffer ) ) EXIT_MAIN ippFree( pMemInit ); ippFree( pSpec ); ippFree( pBuffer ); printf("Exit status %d (%s)\n", (int)status, ippGetStatusString(status)); return (int)status; }