/**
   * Save onscreen image to file - suffix must be png, jpg, or gif.
   *
   * @param filename the name of the file with one of the required suffixes
   */
  public static void save(String filename) {
    File file = new File(filename);
    String suffix = filename.substring(filename.lastIndexOf('.') + 1);

    // png files
    if (suffix.toLowerCase().equals("png")) {
      try {
        ImageIO.write(onscreenImage, suffix, file);
      } catch (IOException e) {
        e.printStackTrace();
      }
    }

    // need to change from ARGB to RGB for jpeg
    // reference:
    // http://archives.java.sun.com/cgi-bin/wa?A2=ind0404&L=java2d-interest&D=0&P=2727
    else if (suffix.toLowerCase().equals("jpg")) {
      WritableRaster raster = onscreenImage.getRaster();
      WritableRaster newRaster;
      newRaster = raster.createWritableChild(0, 0, width, height, 0, 0, new int[] {0, 1, 2});
      DirectColorModel cm = (DirectColorModel) onscreenImage.getColorModel();
      DirectColorModel newCM =
          new DirectColorModel(
              cm.getPixelSize(), cm.getRedMask(), cm.getGreenMask(), cm.getBlueMask());
      BufferedImage rgbBuffer = new BufferedImage(newCM, newRaster, false, null);
      try {
        ImageIO.write(rgbBuffer, suffix, file);
      } catch (IOException e) {
        e.printStackTrace();
      }
    } else {
      System.out.println("Invalid image file type: " + suffix);
    }
  }
  /**
   * Makes the Mandelbrot image.
   *
   * @param width the width
   * @parah height the height
   * @return the image
   */
  public BufferedImage makeMandelbrot(int width, int height) {
    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
    WritableRaster raster = image.getRaster();
    ColorModel model = image.getColorModel();

    Color fractalColor = Color.red;
    int argb = fractalColor.getRGB();
    Object colorData = model.getDataElements(argb, null);

    for (int i = 0; i < width; i++)
      for (int j = 0; j < height; j++) {
        double a = XMIN + i * (XMAX - XMIN) / width;
        double b = YMIN + j * (YMAX - YMIN) / height;
        if (!escapesToInfinity(a, b)) raster.setDataElements(i, j, colorData);
      }
    return image;
  }