//---------------------------------------------------------------------------
void Threshold(PImage im)  {
  for (int i = 0; i < im.width; i++) { 
    for (int j = 0; j < im.height; j++) {
      color c = im.get(i,j);
      int r = (int)(red(c));  
      int g = (int)(green(c));
      int b = (int)(blue(c));
      
      // Wzór na poprawną luminancję
      int w = (int)(0.299 * r + 0.587 * g + 0.114 * b);
      
      w = (w < 128) ? 0 : 255;
      
      im.set(i,j,color(w,w,w));
    }  
  }
  im.updatePixels();
}
//---------------------------------------------------------------------------
Point intToPoint(int value, int size) {
  value--;
  Point p = new Point(0,0);

  if (size == 1) {
    return p;
  }

  int d1 = size-1;
  int d2 = value / d1;
  int d3 = value % d1;
  int d4 = size / d1;

  switch (d2) {
    case 0 : {
      p.x = d3 * d4;
      p.y = 0;
    } break;
    case 1 : {
      p.x = d1;
      p.y = d3 * d4;
    } break;
    case 2 : {
      p.x = d1 - d3 * d4;
      p.y = d1;
    } break;
    case 3 : {
      p.x = 0;
      p.y = d1 - d3 * d4;
    } break;
  }
  return p;
}
//---------------------------------------------------------------------------
int pointToInt(Point p, int size) {
  int value = 0;

  if (p.y == 0) value = p.x;
  else if (p.x == size-1) value = (size -1) + p.y ;
  else if (p.y == size-1) value =  3 * (size-1) - p.x;
  else if (p.x == 0) value = 4 * (size-1) - p.y;

  return ++value;
}
//---------------------------------------------------------------------------