private Image create_image(int n, int m, int k)
  {
    if (this.srcPicArray[k] != null) {
      return this.srcPicArray[k];
    }

    int x = m * this.W;

    int y = n * this.W;
    int w = this.W;
    int h = this.W;
    BufferedImage newpic = null;
    newpic = this.srcImage.getSubimage(x, y, w, h);
    this.srcPicArray[k] = newpic;
    return this.srcPicArray[k];
  }