MulPack

Syntax

Parameters

Description

The function ippiMulPack is declared in the ippi.h file. It operates with ROI (see Regions of Interest in Intel IPP).

This function multiplies corresponding pixel values of two source images, A and B represented in RCPack2D format and stores the result into the destination image C in packed format also. The multiplying is performed according to the following formulas:

ReC = ReA*ReB - ImA*ImB;

ImC = ImA*ReB + ImB*ReA.

Not-in-place flavors multiply pixel values of ROI in the source images pSrc1 and pSrc2, and store result in the pDst.

In-place flavors multiply pixel values of ROI in the source images pSrc and pSrcDst, and store result in the pSrcDst.

In case of operations on integer data, the resulting values are scaled by scaleFactor (see Integer Result Scaling). Note that the functions with AC4 descriptor do not process the alpha channel.

This function can be used in image filtering operations that include FFT transforms. The Example “Using ippiMulPack Function in Image Filtering” illustrates how the horizontal edges of an image can be detected. First, both the source image and the filter are transformed into the frequency domain by applying the forward FFT function which yields results in packed format. Then, actual filtering is performed through multiplying these packed data on a point by point basis using the function ippiMulPack. Finally, filtered data is transformed to the time domain by means of the inverse FFT function.

IppStatus mulpack( void ) {

   Ipp32f tsrc[64], tflt[64], tdst[64];

   Ipp32f fsrc[64], fflt[64], fdst[64];

   IppiFFTSpec_R_32f *spec;

   const IppiSize roiSize8x8 = { 8, 8 }, roiSize3x3 = { 3, 3 };

   const Ipp32f filter[3*3] = {-1,-1,-1, 0,0,0, 1,1,1};

   ippiSet_32f_C1R( 0, tsrc, 8*sizeof(Ipp32f), roiSize8x8 );

   ippiAddC_32f_C1IR( 1, tsrc+8+1, 8*sizeof(Ipp32f), roiSize3x3 );

   ippiSet_32f_C1R( 0, tflt, 8*sizeof(Ipp32f), roiSize8x8 );

   ippiCopy_32f_C1R( filter, 3*sizeof(Ipp32f), tflt, 8*sizeof(Ipp32f), roiSize3x3 );

   ippiFFTInitAlloc_R_32f( &spec, 3, 3, IPP_FFT_DIV_INV_BY_N, ippAlgHintAccurate );

   ippiFFTFwd_RToPack_32f_C1R( tsrc, 8*sizeof(Ipp32f), fsrc, 8*sizeof(Ipp32f), spec, 0 );

   ippiFFTFwd_RToPack_32f_C1R( tflt, 8*sizeof(Ipp32f), fflt, 8*sizeof(Ipp32f), spec, 0 );

   ippiMulPack_32f_C1R( fsrc, 8*sizeof(Ipp32f), fflt, 8*sizeof(Ipp32f), fdst, 8*4, roiSize8x8);

   ippiFFTInv_PackToR_32f_C1R( fdst, 8*sizeof(Ipp32f), tdst, 8*sizeof(Ipp32f), spec, 0 );

   ippiFFTFree_R_32f( spec );

   return 0;

}

Return Values