BufferedImage image1 = new BufferedImage(100, 100, BufferedImage.TYPE_INT_RGB);
BufferedImage image2 = new BufferedImage(100, 100, BufferedImage.TYPE_INT_RGB);

for (int i = 0; i < 100; i++) {
    for (int j = 0; j < 100; j++) {

        int gray = (i + j) + (( i + j) << 8) + ((i + j) << 16);
        image1.setRGB(i, j, gray);
        int bw = 0;
        if (Math.random() * 256 < (i+j)) bw = 0xFFFFFF;
        image2.setRGB(i, j, bw);
    }
}

JFrame window1 = new JFrame();
boolean flip = false;
BufferedImage image;
while (true) {
    if (flip) image = image1;
    else image = image2;
    window1.getContentPane().removeAll();
    window1.setTitle("pic");
    JLabel label = new JLabel(new ImageIcon(image));
    window1.add(label);
    window1.setBounds(100, 100, 100, 200);
    window1.setVisible(true);
    Thread.sleep(500);
    flip = !flip;
}

int main()
{
  const int S = 300; // Размер поля
  const int R = 256; // Диапазон яркостей

  for (int y = 0; y < S; ++y)
  {
    int error = 0;

    for (int x = 0; x < S; ++x)
    {
      int ideal = (x + y) * (R - 1) / (2 * (S - 1));
      int corrected = ideal + error;
      int bw = corrected < R / 2 ? 0 : R - 1;
      error = corrected - bw;

      // Исходное поле: нарисовать точку (x, y) с яркостью `ideal`
      // Дизеринг: нарисовать точку (x, y) с яркостью `bw`
    }
  }
}