Central moment IPL-IPP conversion

b_k_ — Fri, 04 Jul 2014 10:00:28 GMT

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

at the first glance this is

Gennady_F_Intel — Sat, 05 Jul 2014 06:00:12 GMT

at the first glance this is the problem in IPL which is no longer supported. Please use IPP instead. :)

topic Central moment IPL-IPP conversion in Intel® Integrated Performance Primitives

Central moment IPL-IPP conversion

at the first glance this is