e671. 在缓冲图像中存取像素

    // Get a pixel
    int rgb = bufferedImage.getRGB(x, y);
    
    // Get all the pixels
    int w = bufferedImage.getWidth(null);
    int h = bufferedImage.getHeight(null);
    int[] rgbs = new int[w*h];
    bufferedImage.getRGB(0, 0, w, h, rgbs, 0, w);
    
    // Set a pixel
    rgb = 0xFF00FF00; // green
    bufferedImage.setRGB(x, y, rgb);