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iipiSqrDistanceSame_Norm normalization

nose00
Beginner
139 Views
Hello,

I'm using the image proximity measure iipiSqrDistanceSame_Norm and I don't get how the normalization is done.
I have done the calculations on the sample of the manual by myself and I don't get the same results.han

Could anybody help me?
Thanks in advanced,

kind regards
pepa
0 Kudos
4 Replies
Vladimir_Dudnik
Employee
139 Views

Hello,

could you please share piece of code demosntrating how do you use IPP function?

Regards,
Vladimir
nose00
Beginner
139 Views

Hello Vladimir,
here the piece of code. I#m using C#.

float[] source = new float[] {2, 2, 2, 2, 2,
2, 1, 1, 2, 2,
2, 1, 1, 2, 2,
2, 1, 1, 2, 2 };

float[] template = new float[] {1, 1, 2,
1, 1, 2,
1, 1, 2};

float[] dest = new float[5*4];

IppiSize sourceRoi = new IppiSize(5, 4);
IppiSize templateRoi = new IppiSize(3, 3);
int sourceStep = 5*sizeof(float);
int templateStep = 3*sizeof(float);
int destStep = 5*sizeof(float);

fixed(float* pSource = source, pTemplate= tuple, pDest = dest) {
ippResult = ip.ippiSqrDistanceSame_Norm_32f_C1R(pSource, sourceStep, sourceRoi, pTemplate,
tupleStep, templateRoi, pDest, destStep);
}

Result:
0,72 - 0,56 - 0,44 - 0,46 - 1,06
0,44 - 0,29 - 0,10 - 0,17 - 0,87
0,55 - 0,33 - 0,00 - 0,14 - 0,87
0,89 - 0,68 - 0,41 - 0,44 - 1,06

At row 2, column 2 I get the expected 0.00. But for example row 2, column 3,
Formula:
result(2,3) = [tmpl'(0,0)- src'(0.5, 1.5)]^2 + [tmpl'(0,1)- src'(0.5, 2.5)]^2 + [tmpl'(0,2)- src'(0.5, 3.5)]^2 +
[tmpl'(1,0)- src'(0.5, 1.5)]^2 + [tmpl'(1,1)- src'(0.5, 2.5)]^2 + [tmpl'(1,2)- src'(0.5, 3.5)]^2 +
[tmpl'(2,0)- src'(0.5, 1.5)]^2 + [tmpl'(2,1)- src'(0.5, 2.5)]^2 + [tmpl'(2,2)- src'(0.5, 3.5)]^2

tmpl' and src' are the normalized template and source.
I guess, that the point(0.5, 1.5) is rounded to (1,2).

For the row 2, column 3 I don't get 0.14, so I guess I'm not normalizing well. (src'(r,c)= src(r,c)/length
I tried different lengths :
- sqrt(elements^2 of the 3x3 part of the source imgage)
- sqrt(elements^2 of the whole image ??)
and other just to test, but I don't get 0,14

Thanks a lot,
regards pepa


Igor_B_Intel1
Employee
139 Views
Hi,
SSD values in function with "Same_" suffics are normalized by auto-correlations of source and template images in pixelneighborhood. I manually checked (2,3) pixel and got result(2,3) = 3/sqrt(18*27)=0.14.
Please read "Image Proximity Measures" section in ippiman document for more details.

Igor.
nose00
Beginner
139 Views
Hi,
SSD values in function with "Same_" suffics are normalized by auto-correlations of source and template images in pixelneighborhood. I manually checked (2,3) pixel and got result(2,3) = 3/sqrt(18*27)=0.14.
Please read "Image Proximity Measures" section in ippiman document for more details.

Igor.

Hi Igor,
thanks a lot for the answer.

Kind regards
Pepa
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