Merge HTML to Image in Java

Presentation presentation = new Presentation();
try {
    presentation.getSlides().removeAt(0);

    FileInputStream firstHtmlStream = new FileInputStream("file1.html");
    try {
        presentation.getSlides().addFromHtml(firstHtmlStream);
    } finally {
        firstHtmlStream.close();
    }

    FileInputStream secondHtmlStream = new FileInputStream("file2.html");
    try {
        presentation.getSlides().addFromHtml(secondHtmlStream);
    } finally {
        secondHtmlStream.close();
    }

    for (ISlide slide : presentation.getSlides()) {
        IImage slideImage = slide.getImage(1f, 1f);
        try {
            slideImage.save("slide_" + slide.getSlideNumber() + ".png", ImageFormat.Png);
        } finally {
            slideImage.dispose();
        }
    }
} finally {
    presentation.dispose();
}