Hello and good day.
When converting from the old IPL to the IPP library (v8.1) I get strange results for the IPL function for central moment.
Example code:
int width = 103; // minimum size for the discrepancy
int height =2;
// create unsigned char image (w,h)=(103,2)
IplImage* iplIm = iplCreateImageHeader(1, 0, IPL_DEPTH_8U, "GRAY", "GRAY",
IPL_DATA_ORDER_PIXEL, IPL_ORIGIN_TL,
IPL_ALIGN_QWORD, width, height,
NULL, NULL, NULL, NULL);
// set all pixels to 1.
iplAllocateImage(iplIm, 1, 1);
//create ipp state for moments
IppHintAlgorithm hint = ippAlgHintAccurate;//ippAlgHintAccurate;//ippAlgHintFast;// ippAlgHintNone
// allocate memory for state
IppiMomentState_64f* pState;
IppStatus sts = ippiMomentInitAlloc_64f( &pState, hint);
// calculate moments
IppiSize size = {width, height};
sts = ippiMoments64f_8u_C1R((Ipp8u*)iplIm->imageData, iplIm->widthStep, size, pState);
// get central moment for IPL and IPP
int mOrd = 3;
int nOrd = 0;
double res_ipp;
sts = ippiGetCentralMoment_64f( pState, mOrd, nOrd, 0, &res_ipp);
double res_ipl = iplCentralMoment(iplIm, mOrd, nOrd);
assert(res_ipl == res_ipp);
Results:
Third moment should be zero for an image consisting only of ones.
IPP: -7.4505805969238281e-009, Good enough
IPL: -2.0000000074505806, ???
System details:
I7-2600, Win7 32bit, IPP8.1SP1.
Loaded IPP dlls:
ippccg9-8.1.dll
ippsg9-8.1.dll
ippcvg9-8.1.dll
ippig9-8.1.dll
