void Laplace (ImSize, InIm, OutIm)
int  ImSize;
BYTE ** InIm;
int  ** OutIm;
{
   int   r,c, y,x, Sum;

   static int Mask [3][3] = { { 0,  1, 0},
                              { 1, -4, 1},
                              { 0,  1, 0} };

   for (r=0; r<ImSize; r++)
      for (c=0; c<ImSize; c++)  OutIm [r][c] = 0;

   for (r=1; r<ImSize-1; r++) {
      for (c=1; c<ImSize-1; c++) {
         Sum = 0;
         for (y=-1; y<=1; y++)
            for (x=-1; x<=1; x++)
               Sum += InIm [r+y] [c+x] * Mask [y+1] [x+1];
         OutIm [r][c] = Sum/9;
}  }  }
