fconvol.c

image processing including fourier,wavelet,segmentation etc.

/*----------------------Megawave2 Module-----------------------------------*/
/*mwcommand
  name = {fconvol};
  version = {"1.1"};
  author = {"Jacques Froment"};
  function = {"2D-direct convolution of a fimage"};
  usage = {
            in->in "Input fimage",
            filter->filtre "convolution filter (fimage)",
            out<-out "Output fimage"
          };
*/
/*----------------------------------------------------------------------
 v1.1: fixed kmin/lmin/dyS bugs (L.Moisan)
----------------------------------------------------------------------*/

#include <stdio.h>
#include <math.h>
 
#include "mw.h"

#define min(a,b)        (((a)>(b)) ? (b) : (a))
#define max(a,b)        (((a)>(b)) ? (a) : (b))


void fconvol(in,filtre,out)
     Fimage in,filtre,out;
{
  int n,m,k,l,dxS,dyS,kmax,kmin,lmax,lmin,K2,L2;
  double S;
  float *ptrO,*ptrI,*ptrF;
  
  out=mw_change_fimage(out,in->nrow,in->ncol);
  if (!out) mwerror(FATAL,1,"not enough memory\n"); 
  
  K2 = filtre->ncol / 2;
  L2 = filtre->nrow / 2;
  dxS = in->ncol;
  dyS = in->nrow;
  ptrO = out->gray;
  ptrI = in->gray;
  
  for(m=0;m<in->nrow;m++) 
    for (n=0;n<in->ncol;n++) 
      {
	S = 0.0;
	kmax = min(filtre->ncol-1,n+K2);
	kmin = max(0,1+n+K2-dxS);
	lmax = min(filtre->nrow-1,m+L2);
	lmin = max(0,1+m+L2-dyS);
	
	ptrF = filtre->gray;
	for (l=lmin;l<=lmax;l++) 
	  for (k=kmin;k<=kmax;k++) 
	    S += ptrI[dxS*(m-l+L2) + (n-k+K2)] * ptrF[filtre->ncol*l+k];
	*ptrO++ = (float) S;
      }
}