Core point detection

Question

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Hello friends,

I am doing a project of fingerprint matching.
For that I need to find core point.
The method which I have used is poincare index, but I am not getting the output and I dont know the reason.
please help...

C#

Double PIby2=Math.PI/2;
           Double[,] Poincare = new Double[blockW - 1, blockH - 1];
           for (x = 1; x < blockW - 1; x++)
           {
               for (y = 1; y < blockH - 1; y++)
               {
                           Double x1 = thetaD[x, y - 1] - thetaD[x + 1, y - 1];
                           Double x2=thetaD[x - 1, y - 1] - thetaD[x, y - 1];
                           Double x3=thetaD[x - 1, y] - thetaD[x - 1, y - 1];
                           Double x4=thetaD[x - 1, y + 1] - thetaD[x - 1, y];
                           Double x5=thetaD[x, y + 1] - thetaD[x - 1, y + 1];
                           Double x6=thetaD[x + 1, y + 1] - thetaD[x, y + 1];
                           Double x7=thetaD[x + 1, y] - thetaD[x + 1, y + 1];
                           Double x8=thetaD[x + 1, y - 1] - thetaD[x + 1, y];
                   if(x1<PIby2) x1=x1;
                   else if(x1< -PIby2) x1=Math.PI+x1;
                   else x1=Math.PI-x1;
                     if(x2<PIby2) x2=x2;
                   else if(x2<-PIby2) x2=Math.PI+x2;
                   else x2=Math.PI-x2;
                     if(x3<PIby2) x3=x3;
                   else if(x3<-PIby2) x3=Math.PI+x3;
                   else x3=Math.PI-x3;
                     if(x4<PIby2) x4=x4;
                   else if(x4<-PIby2) x4=Math.PI+x4;
                   else x4=Math.PI-x4;
                     if(x5<PIby2) x5=x5;
                   else if(x5<-PIby2) x5=Math.PI+x5;
                   else x5=Math.PI-x5;
                     if(x6<PIby2) x6=x6;
                   else if(x6<-PIby2) x6=Math.PI+x6;
                   else x6=Math.PI-x6;
                     if(x7<PIby2) x7=x7;
                   else if(x7<-PIby2) x7=Math.PI+x7;
                   else x7=Math.PI-x7;
                     if(x8<PIby2) x8=x8;
                   else if(x8<-PIby2) x8=Math.PI+x8;
                   else x8=Math.PI-x8;
                  Poincare[x,y]=Math.Abs((x1+x2+x3+x4+x5+x6+x7+x8)/(2*Math.PI));
               }
           }
           for (x = 1; x < blockW - 1; x++)
           {
               for (y = 1; y < blockH - 1; y++)
               {
                   if (Poincare[x, y] < 0.45 || Poincare[x, y] > 0.51)
                   {
                   }
                   else
                   {

                               image.SetPixel(x , y, Color.Blue);
                       }
                   }
               }
           }

Posted 1-Apr-11 19:01pm

Noel3090

Updated 12-May-18 2:31am

Dalek Dave

v2

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Dalek Dave 4-Apr-11 16:37pm

Edited for Grammar.

2 solutions

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Valery Possoz · Answer 1 · 2011-04-02T05:08:00

Solution 1

Hi,

There is an article about fingerprint recognition on this website:

A Framework in C# for Fingerprint Verification[^]

Maybe it could help you solving your issues.

Valery.

Posted 2-Apr-11 5:08am

Valery Possoz

Comments

Dylan Morley 4-Apr-11 12:09pm

Comment from OP: thanks valery, but i wanted code for poincare index.... please help!

Noel3090 4-Apr-11 12:10pm

thanks valery, but i wanted code for poincare index , please help!!

Dalek Dave 4-Apr-11 16:37pm

Good Links

BobJanova · Answer 2 · 2011-04-04T06:41:00

Solution 3

These pieces of code

C#

if(x1<PIby2) x1=x1;
else if(x1< -PIby2) x1=Math.PI+x1;
else x1=Math.PI-x1;

I suspect you want each angle within +/- PI/2. That would be

C#

if(x1>PIby2) x1=x1-Math.PI;
else if(x1< -PIby2) x1=Math.PI+x1;

Also, it would be better to have an array rather than eight variables so you didn't have to write the same code eight times!

I do not know the Poincaré index but that looks like a mistake and it will invalidate the results.

Posted 4-Apr-11 6:41am

BobJanova

Comments

Dalek Dave 4-Apr-11 16:38pm

Good Answer.

Member 10348471 22-Oct-13 3:32am

can u help me 2 in finding this core point...????

Noel3090 5-Apr-11 13:49pm

thanks BobJanova

Member 11115090 9-Mar-15 4:54am

hi I have the same project and need c# code to find core and delta in fingerprint images. please help me
I search very much and can not find any things my project load image threshold and erode and dilate and grayscale image but i can not find core and delta i cannot compute angle and cannot find arc of image
my project work with aforge.net library in c#
please please please help me for this code