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

ID 790148
Date 6/24/2024
Public

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Document Table of Contents

DFTFwd

Applies forward discrete Fourier transform to an image.

Syntax

Case 1: Not-in-place operation on floating-point data

IppStatus ippiDFTFwd_RToPack_<mod>(const Ipp32f* pSrc, int srcStep, Ipp32f* pDst, int dstStep, const IppiDFTSpec_R_32f* pDFTSpec, Ipp8u* pBuffer);

Supported values for mod:

32f_C1R

32f_C3R

32f_C4R

32f_AC4R

Case 2: Not-in-place operation on complex data

IppStatus ippiDFTFwd_CToC_32fc_C1R(const Ipp32fc* pSrc, int srcStep, Ipp32fc* pDst, int dstStep, const IppiDFTSpec_C_32fc* pDFTSpec, Ipp8u* pBuffer);

Case 3: In-place operation on floating-point data

IppStatus ippiDFTFwd_RToPack_<mod>(Ipp32f* pSrcDst, int srcDstStep, const IppiDFTSpec_R_32f* pDFTSpec, Ipp8u* pBuffer);

Supported values for mod:

32f_C1IR

32f_C3IR

32f_C4IR

32f_AC4IR

Case 4: In-place operation on complex data

IppStatus ippiDFTFwd_CToC_32fc_C1IR(Ipp32fc* pSrcDst, int srcDstStep, const IppiDFTSpec_C_32fc* pDFTSpec, 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.

pDFTSpec

Pointer to the previously initialized DFT context structure.

pBuffer

Pointer to the external work buffer.

Description

This function operates with ROI.

This function performs a forward DFT on each channel of the source image ROI pSrc (pSrcDst for in-place flavors) and writes the Fourier coefficients into the corresponding channel of the destination buffer pDst (pSrcDst for in-place flavors).

The function flavor ippiDFTFwd_RToPack that operates on images with real data takes advantage of the symmetry property and stores the output data in RCPack2D format. It supports processing of the 1-, 3-, and 4-channel images. Note that the functions with AC4 descriptor do not process alpha channel.

The function flavor ippiDFTFwd_CToC that operates on images with complex data performs no packing of the transform results as no symmetry with respect to frequency domain data is observed in this case. Memory layout of images with complex data follows the same conventions as for real images provided that each pixel value consists of two numbers: imaginary and real part.

Before using the forward DFT functions, you need to compute the size of the work buffer by ippiDFTGetSize and initialize the context structure by the ippiDFTInit function. The forward DFT functions use the pDFTSpec 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 if pSrc, pDst, or pDFTSpec pointer is NULL.

ippStsStepErr

Indicates an error condition if srcStep or dstStep value is zero or negative.

ippStsContextMatchErr

Indicates an error condition if a pointer to an invalid pDFTSpec structure is passed.

ippStsMemAllocErr

Indicates an error condition if memory allocation fails.

See Also