DctMod2 Feature For Face Recognition

There has been an lot emphasis on the following feature in face recognition papers after 2002
It seems the recognition rate increases whatever classifier you use with the feature
Following is the C Code To be used with Opencv


You can refer the following paper

Fast feature extraction method for robust face verification
C. Sanderson and K.K. Paliwal

http://maxwell.me.gu.edu.au/spl/publications/papers/el02_conrad.pdf

Another Paper by Sanderson and Bengio is there on DCTmod3 coefficients

But Today DCTMOD2 rules

  

#include "cv.h"

#include "cvaux.h"

#include 

#include 



void  featureDctMod2(IplImage * img,float*  features_final)

{

    int Nx = floor((img->width - 4)/4);

    int Ny= floor((img->height - 4)/4);

    float* observations = (float*)malloc(  Nx*Ny * 25 * sizeof(float) );

    float* features = (float*)malloc(  Nx*Ny * 18 * sizeof(float) );

    cvImgToObs_DCT(img,observations, cvSize(8,8),cvSize(5,5),cvSize(4,4) );

    int i,j,k=0;

    for (i=0;i    {

        for (j=0;j        {

/*

0   1   2    3    4

5   6   7    8    9

10  11  12   13  14

15  16  17   18  19

20  21  22   23  24



Zig Zag Pattern

0,1,5,10,6,2,3,7,11,15,20,16,12,8,4



*/



// Zig Zag 15 features + 3 for dct mod2

            features[i*18*Nx + j*18 +0]=observations[i*25*Nx + j*25 +0]; 

// not putting zero , might cause scale problem

            features[i*18*Nx + j*18 +1]=observations[i*25*Nx + j*25 +1];

            features[i*18*Nx + j*18 +2]=observations[i*25*Nx + j*25 +5];

            features[i*18*Nx + j*18 +3]=observations[i*25*Nx + j*25 +0];

            features[i*18*Nx + j*18 +4]=observations[i*25*Nx + j*25 +1];

            features[i*18*Nx + j*18 +5]=observations[i*25*Nx + j*25 +5];

            features[i*18*Nx + j*18 +6]=observations[i*25*Nx + j*25 +10];

            features[i*18*Nx + j*18 +7]=observations[i*25*Nx + j*25 +6];

            features[i*18*Nx + j*18 +8]=observations[i*25*Nx + j*25 +2];

            features[i*18*Nx + j*18 +9]=observations[i*25*Nx + j*25 +3];

            features[i*18*Nx + j*18 +10]=observations[i*25*Nx + j*25 +7];

            features[i*18*Nx + j*18 +11]=observations[i*25*Nx + j*25 +11];

            features[i*18*Nx + j*18 +12]=observations[i*25*Nx + j*25 +15];

            features[i*18*Nx + j*18 +13]=observations[i*25*Nx + j*25 +20];

            features[i*18*Nx + j*18 +14]=observations[i*25*Nx + j*25 +16];

            features[i*18*Nx + j*18 +15]=observations[i*25*Nx + j*25 +12];

            features[i*18*Nx + j*18 +16]=observations[i*25*Nx + j*25 +8];

            features[i*18*Nx + j*18 +17]=observations[i*25*Nx + j*25 +4];

            for (k=0;k<18;k++)

            {

                   features_final[i*18*Nx + j*18 +k]= features[i*18*Nx + j*18 +k];

            }

        }



    }

    for (i=1;i    {



        for (j=1;j        {

   //Calculate Horizontal Delta and Vertical Delta

            features_final[i*18*Nx + j*18 ]=(-features[i*18*Nx + (j-1)*18 +3] +features[i*18*Nx + (j+1)*18 +3])/2;

            features_final[i*18*Nx + j*18 +1]=(-features[i*18*Nx + (j-1)*18 +4] +features[i*18*Nx + (j+1)*18 +4])/2;

            features_final[i*18*Nx + j*18 +2]=(-features[i*18*Nx + (j-1)*18 +5] +features[i*18*Nx + (j+1)*18 +5])/2;

            features_final[i*18*Nx + j*18 +3]=(-features[(i-1)*18*Nx + j*18 +3] +features[(i+1)*18*Nx + j*18 +3])/2;

            features_final[i*18*Nx + j*18 +4]=(-features[(i-1)*18*Nx + j*18 +4] +features[(i+1)*18*Nx + j*18 +4])/2;

            features_final[i*18*Nx + j*18 +5]=(-features[(i-1)*18*Nx + j*18 +5] +features[(i+1)*18*Nx + j*18 +5])/2;

        }

    }

free(features);

free(observations);

}



void main()

{

IplImage * img = cvLoadImage("sample.jpg",0);



/* Maximum number of Blocks */

int Nx = floor((img->width - 4)/4);

int Ny= floor((img->height - 4)/4);

/* Feature first 6 coefficients are the delta coefficients and rest 12 are from the zig zag order */

float* features = (float*)malloc(  Nx*Ny * 18 * sizeof(float) );



featureDctMod2(img,features);

cvNamedWindow( "Source", 1 );

cvShowImage( "Source", img  );

cvWaitKey(0);

}