/***********************************************************************
 *
 * File: pgmfilter.c (25-May-2001)
 *                   (27-May-2005)
 *
 * Glaetten eines Schwarzweissbildes [Pixelmap im (ASCII) PGM-Format]
 *
 *   Jedes Pixel (Grauwert) wird durch den Mittelwert der m*m
 *   Nachbarpixel ersetzt.
 *  
 * infile....Originalbild (PGM-File mit maxgray=255 und 17 Pixel/Zeile)
 * m.........Filterbreite in Pixel (ungerade)
 * outfile...geglaettetes Bild
 *
 **********************************************************************/

#include <stdio.h>
#include <stdlib.h>

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

/**********************************************************************/

void smooth(unsigned char **imgs,unsigned char **img,\
            int nx,int ny,int m) {

/**********************************************************************/

  int is,ix,iy,jx,jy,k;
  
  for(ix=0;ix<=nx-1;ix=ix+1) {
    for(iy=0;iy<=ny-1;iy=iy+1) {
      k=0;
      is=0;
      for(jx=max(ix-m/2,0);jx<=min(ix+m/2,nx-1);jx=jx+1) {
	for(jy=max(iy-m/2,0);jy<=min(iy+m/2,ny-1);jy=jy+1) {
	  k=k+1;
	  is=is+img[jx][jy];
	}
      }
      imgs[ix][iy]=is/k;
    }
  }
  
}

/**********************************************************************/

int main() {

/**********************************************************************/

  FILE *fpi,*fpo;
  char fname[80],pnm[3];
  unsigned char **img,**imgs;
  int ix,iy,k,m,maxgray,nx,ny;
  
  printf("infile=");
  scanf("%s",fname);

  fpi=fopen(fname,"r");

  fscanf(fpi,"%s",pnm);
  fscanf(fpi,"%d %d",&nx,&ny);
  fscanf(fpi,"%d",&maxgray);
  fgetc(fpi);

  img=(unsigned char**)malloc(nx*sizeof(unsigned char*));
  imgs=(unsigned char**)malloc(nx*sizeof(unsigned char*));
  for(ix=0;ix<=nx-1;ix=ix+1) {
    img[ix]=(unsigned char*)malloc(ny*sizeof(unsigned char));
    imgs[ix]=(unsigned char*)malloc(ny*sizeof(unsigned char));
  }
  
  for(iy=0;iy<=ny-1;iy=iy+1) {
    for(ix=0;ix<=nx-1;ix=ix+1) {
      fscanf(fpi,"%d",&img[ix][iy]);
    }
  }
  
  fclose(fpi);

  for(;;) {
    printf("m=");
    scanf("%d",&m);
    if(m%2==1) {
      break;
    }
  }

  smooth(imgs,img,nx,ny,m);
  
  printf("outfile=");
  scanf("%s",fname);

  fpo=fopen(fname,"w");

  fprintf(fpo,"%s\n",pnm);
  fprintf(fpo,"%d %d\n",nx,ny);
  fprintf(fpo,"%d\n",maxgray);

  k=0;
  for(iy=0;iy<=ny-1;iy=iy+1) {
    for(ix=0;ix<=nx-1;ix=ix+1) {
      k=k+1;
      if(k<17) {
	fprintf(fpo,"%3d ",imgs[ix][iy]);
      } else {
	k=0;
	fprintf(fpo,"%3d \n",imgs[ix][iy]);
      }
    }
  }
  
  fclose(fpo);
  
  return 0;
  
}

/**********************************************************************/