comphisteq.c

eye detection sample in matlab. Eyetrackers can analyze a driver’s level of attentiveness while driv

#include "mex.h"

#define LOW_BOUND 30
#define HIGH_BOUND 220
#define IN_BOUND_PERCENTAGE 170
/* mexFunction is the gateway routine for the MEX-file. */ 
void
mexFunction( int nlhs, mxArray *plhs[],
             int nrhs, const mxArray *prhs[] )
{
  int        i,m,n, comph, compw;
  unsigned char *in,*out,*searchpos;
  unsigned short *x,*y;
  // [sample,y,x] = fdprep(image,searchpos)
  if (nlhs!=3)
      mexErrMsgTxt("Must have exactly 3 outputs [sample,y,x] = fdprep (...)\n");
  if (nrhs!=4)
      mexErrMsgTxt("Must have exactly 4 inputs: image,searchpos, component height, comp width .\n");
  if ((!mxIsUint8(prhs[0]))||(!mxIsUint8(prhs[1])))
      mexErrMsgTxt("Both inputs must be of type UINT8.\n");
  
  in= (unsigned char*)mxGetData(prhs[0]);
  searchpos = (unsigned char*)mxGetData(prhs[1]);
  m=mxGetM(prhs[0]);
  n=mxGetN(prhs[0]);
  if ((mxGetM(prhs[1])!=m)||(mxGetN(prhs[1])!=n))
    mexErrMsgTxt("Both input matrices must be of the same size");

  comph = (int)(*mxGetPr(prhs[2]));
  compw = (int)(*mxGetPr(prhs[3]));
  mexPrintf("w = %d, h = %d\n", compw, comph);
  if ((m<comph)||(n<compw))
    return;
  
  out = mxCalloc(comph*compw*(m-20+1)*(n-20+1),sizeof(char));
  y = mxCalloc((m-20+1)*(n-20+1),sizeof(short));
  x = mxCalloc((m-20+1)*(n-20+1),sizeof(short));
  {
    int size;
    unsigned char* pchar;
    unsigned short* pshort;
    size=DoCalc(in,searchpos,out,x,y,n,m,compw,comph);
    plhs[0] = mxCreateNumericMatrix(comph*compw,size,mxUINT8_CLASS,mxREAL);
    pchar = (unsigned char*)mxGetData(plhs[0]);
    for (i=0; i<size*comph*compw; i++)
        pchar[i]=out[i];
    mxFree(out);
    
    plhs[1] = mxCreateNumericMatrix(1,size,mxUINT16_CLASS,mxREAL);
    pshort = (unsigned short*)mxGetData(plhs[1]);
    for (i=0; i<size; i++)
        pshort[i]=y[i];
    mxFree(y);

    plhs[2] = mxCreateNumericMatrix(1,size,mxUINT16_CLASS,mxREAL);
    pshort = (unsigned short*)mxGetData(plhs[2]);
    for (i=0; i<size; i++)
        pshort[i]=x[i];
    mxFree(x); 
  }
}


int DoCalc(unsigned char *in,
           unsigned char *searchpos,
           unsigned char *out,
           unsigned short *x_array, 
           unsigned short* y_array, 
           int w, 
           int h,
           int compw, 
           int comph)
{
	int i,j,curr,x,y;
	double sum,sqsum,var;
	int hist[256];
	char str[100];
	unsigned char* pout=out;
	int sample_index=0;
	// initializations
	curr=0;
	
	// build histogram
	for (y=0; y<=h-comph;y++)
	{
		for (x=0; x<=w-compw; x++)
		{
			int index =0;
			int offset = y+x*h;
            if (searchpos[offset]==0)
                continue;
			for(i=0; i<256; i++)
				hist[i]=0;
			sum=0;
			sqsum=0;
    		for (j=0; j<compw;j++)
			{
    			for (i=0; i<comph;i++)
			    {
    				pout[index]=in[offset+i+j*h];
				    hist[pout[index]]++;
    				index++;
			    }
			}
			// build probability density function
			for (i=1; i<256;i++)
				hist[i]= hist[i]+hist[i-1];
			for (i=0; i<256;i++)
				hist[i]= hist[i]*255/comph/compw;
			
			// apply histogram equalization
			for (i=0; i<comph*compw; i++)
				pout[i]=hist[pout[i]];
			x_array[sample_index]=x+1;
			y_array[sample_index]=y+1;
			sample_index++;
			pout+=comph*compw;
		}
	}
	
	return sample_index;
}