Erroneous histogram calculation on Multicore

[Kishor_D_]

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

[Ying_H_Intel]

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

[Kishor_D_]

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();

[Kishor_D_]

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();

[Igor_B_Intel1 · Accepted solution]

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

[Kishor_D_]

Thanks Igor,

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