topic Erroneous histogram calculation on Multicore in Intel® Integrated Performance Primitives

Erroneous histogram calculation on Multicore

Kishor_D_ — Wed, 02 Nov 2011 14:02:47 GMT

Hi,
I tried DMIP Histogram Node .
It is giving correct results for histogram of an image for single core platform(P4).

This I verified by summing all histogram value and came equal to size(height*width) of an image

But same code ,I compiled on (i7 ,Dual core ) platform and executed ,histogram values are not matching.

I feel its because DMIP would carrying out histogram operation parallely on different cores.

Can someone justify?
Any quick help would be greatly appreciated.

Thanks in advance ,
Kishor

Erroneous histogram calculation on Multicore

Ying_H_Intel — Thu, 03 Nov 2011 08:22:53 GMT

Hi Kishor,

Could you please provide a test case for the problem? You may use private to attach the file if it is confidential.

Best Regards,
Ying

Erroneous histogram calculation on Multicore

Kishor_D_ — Tue, 08 Nov 2011 07:11:49 GMT

We have tested for various images like, lena.jpg, barbara.jpg, woman.jpg, cameraman.jpg.
Test platforms are :
1. Intel P4
2. Intel dual-core
3.Intel i-7 (2600)

code:

// Node creation
Image *A=&img1;
Image *D=&dst;
// Source nodes
SrcNode *in1=new SrcNode();
in1->Init(A);

//
Scalar nLevels(256);
Scalar lowerLevel(0);
Scalar upperLevel(256);

HistogramNode *hgNode = new HistogramNode();
hgNode->Init(nLevels,lowerLevel,upperLevel);

Store *hgStoreNode = new Store(1,sizeof(int)*256);

DstStoreNode *out= new DstStoreNode();

out->Init(hgStoreNode);

Graph *g = new Graph();
g->Add(in1);
g->Add(hgNode);
g->Add(out);

g->Link(0,0,1,0);
g->Link(1,0,2,0);

g->Compile(img->width,img->height);
g->Execute();

int *histo;

histo=(int*)hgStoreNode->BufferPtr();

Erroneous histogram calculation on Multicore

Kishor_D_ — Tue, 08 Nov 2011 07:14:34 GMT

We have tested it for lena.jpg, camra.jpg, woman.jpg.

Test Platforms:
1. Intel P4
2. Intel dual-core
3. Intel i-7(2660)

Sample code:

//Node creation
Image *A=&img1;
Image *D=&dst;
// Source nodes
SrcNode *in1=new SrcNode();
in1->Init(A);

///
Scalar nLevels(256);
Scalar lowerLevel(0);
Scalar upperLevel(256);

HistogramNode *hgNode = new HistogramNode();
hgNode->Init(nLevels,lowerLevel,upperLevel);

Store *hgStoreNode = new Store(1,sizeof(int)*256);

DstStoreNode *out= new DstStoreNode();

out->Init(hgStoreNode);

Graph *g = new Graph();
g->Add(in1);
g->Add(hgNode);
g->Add(out);

g->Link(0,0,1,0);
g->Link(1,0,2,0);

g->Compile();
g->Execute();

int * histo=(int*)hgStoreNode->BufferPtr();

Erroneous histogram calculation on Multicore

Igor_B_Intel1 — Tue, 08 Nov 2011 10:15:00 GMT

Hi,
Need to use HistogramStore object instead of Store object for correct histogram accumulation. That why you observe wrong results in multi core environtment.

Igor S. Belyakov

Erroneous histogram calculation on Multicore

Kishor_D_ — Tue, 08 Nov 2011 11:57:31 GMT

Thanks Igor,

We tried it using HistogramStore object. It's working fine.