private static void drawCross(Coord c, float greyVals[][], int size) {
    for (int s = 0 ; s < size ; s++) {
      try { greyVals[c.x + s][c.y] = 1 ; } catch (Exception e) {}
      try { greyVals[c.x - s][c.y] = 1 ; } catch (Exception e) {}
      try { greyVals[c.x][c.y + s] = 1 ; } catch (Exception e) {}
      try { greyVals[c.x][c.y - s] = 1 ; } catch (Exception e) {}
    }
  }