minima.c

feret人脸图象数据库处理代码

/*----------------------------------------------------------------------
PROGRAM: minima.c
DATE:    3/9/94
AUTHOR:  Baback Moghaddam, [e-mail]
------------------------------------------------------------------------

  This function computes the local minima of an input array and
  returns them sorted in ascending order in the pre-allocated 
  Points structure

  minima(float **array, int imin, int imax, int jmin, int jmax,
         Points *myPoints)	

  (imin,imax,jmin,jmax) specify the regions over which the minima
  detection is to be carried out

---------------------------------------------------------------------- */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <float.h>
#include "util.h"
#include "io.h"


struct Points {
  int n;
  int *x;
  int *y;
  float *f;
};

struct Point {
  int x;
  int y;
  float f;
};


int compare(struct Point **p1, struct Point **p2);

void minima(float **A, int imin, int imax, int jmin, int jmax,
	    struct Points *Ps);




void minima(float **A, int imin, int imax, int jmin, int jmax,
	    struct Points *Ps)
{

  register int i,j;
  int N, c;
  int *X, *Y;
  float *F, f;
  struct Point *P;
  struct Point **Pp;
  
  N = (imax-imin)*(jmax-jmin)/9.0;   /* max # of minima possible */

  P  = malloc(sizeof(struct Point) * N);
  Pp = malloc(sizeof(struct Point *) * N);


  /* run 3-by-3 minima detector over region of interest */
  c = 0;
  for (i=imin+1; i<imax; i++) 
    for (j=jmin+1; j<=jmax; j++) {
      
      f = A[i][j]; 
      if (A[i-1][j-1]>f && A[i-1][j]>f && A[i-1][j+1]>f && \
	  A[i][j-1]>f   && A[i][j+1]>f && \
	  A[i+1][j-1]>f && A[i+1][j]>f && A[i+1][j+1]>f) {
	
	P[c].x = i;
	P[c].y = j;
	P[c].f = f;
	Pp[c] = &(P[c]);
	c++;
      }
    }
  N = c;

  /* sort Point array */
  qsort(Pp, N, sizeof(struct Point *),
	(int (*)(void **, void **)) compare);
  

  /* copy the minima into the Points structure */
  Ps->n = N;
  for (i=0; i<N; i++) {
    Ps->x[i+1] = Pp[i]->x;
    Ps->y[i+1] = Pp[i]->y;
    Ps->f[i+1] = Pp[i]->f;
  }

  /* free up structures */
  free(P);
  free(Pp);

}
  

int compare(struct Point **p1, struct Point **p2)
{
  int r=0;

  if ((*p1)->f < (*p2)->f)
    r = -1;
  else if ((*p1)->f > (*p2)->f)
    r = +1;
  
  return r;
}