topic even mask ippiFilterColumn_32f_C1R in Intel® Integrated Performance Primitives

even mask ippiFilterColumn_32f_C1R

seiji-torigoe — Mon, 05 Sep 2005 15:32:30 GMT

1. I want to calculate the average of y.
2. When the size of the mask is an even number, it is incorrect.
(Pen3 i820 WinXpSp1 IPP4.1.22)
3. Is there something alternative proposal?

// sample code
void main(void)
{
Ipp32f *pSrc; int SrcW, SrcH, SrcS;
Ipp32f *pDst; int DstW, DstH, DstS;
Ipp32f *pMsk; int MskSize;
Ipp32f *pTmp; int yAnchor, x;

IppStatus Status;
IppiSize SrcSize, DstSize;

SrcW = 5; SrcH = 4;
pSrc = ippiMalloc_32f_C1(SrcW, SrcH, &SrcS);
SrcSize.width = SrcW; SrcSize.height = SrcH;
Status = ippiSet_32f_C1R(1.0f, pSrc, SrcS, SrcSize);

MskSize = SrcH;
pMsk = ippsMalloc_32f(MskSize);
Status = ippsSet_32f(1.0f / MskSize, pMsk, MskSize);

DstW = SrcW; DstH = 1;
pDst = ippiMalloc_32f_C1(DstW, DstH, &DstS);

yAnchor = (MskSize - 1) / 2;
pTmp = pSrc + (SrcS / sizeof(Ipp32f)) * yAnchor;
DstSize.width = DstW; DstSize.height = DstH;
Status = ippiFilterColumn_32f_C1R(
pTmp, SrcS, pDst, DstS, DstSize,
pMsk, MskSize, yAnchor);
printf("Status = %d ", Status);
pTmp = pDst;
for ( x = 0; x < DstW; x++ )
{
printf("%f ", *pTmp); pTmp++;
}

ippiFree(pDst);
ippsFree(pMsk);
ippiFree(pSrc);

printf("push any key "); getch();
}

Re: even mask ippiFilterColumn_32f_C1R

Vladimir_Dudnik — Thu, 08 Sep 2005 23:43:59 GMT

Hi,

there is answer from our expert:

seemsyou forget (or misread) that arbitrary kernels for filtering operations are used in inverse order (the same as for FIR), therefore anchor should be treated in inverse order too:

pTmp = pSrc + (SrcS /

sizeof(Ipp32f)) * ( MskSize - yAnchor - 1 );

The best way for calculating average is FilterBox or SumColumn function they are faster because dont use muls.

Regards,

Vladimir

Re: even mask ippiFilterColumn_32f_C1R

seiji-torigoe — Fri, 09 Sep 2005 07:51:56 GMT

Thanks.
I understood it.
Thanks.