import java.io.*;
    import java.util.zip.*;
 
    File rootDir = engine.getInterpretedOutputDirectory();
    File slidesDir = new File(rootDir, engine.getSlideDirectory());
 
    ZipOutputStream out = new ZipOutputStream(new FileOutputStream(new File(rootDir, "images.zip")));
    out.setLevel(Deflater.DEFAULT_COMPRESSION);
    byte[] buffer = new byte[18024];
    File[] imageFiles = slidesDir.listFiles();
    for (File f : imageFiles) {
        if (f.isDirectory() || f.getName().toLowerCase().endsWith(".html")) continue;
        FileInputStream in = new FileInputStream(f);
        out.putNextEntry(new ZipEntry(f.getName()));
        int len;
        while ((len = in.read(buffer)) > 0) {
            out.write(buffer, 0, len);
        }
        out.closeEntry();
        in.close();
    }
    out.close();