public void merg() throws IOException
    {
       List<String> tifs = new ArrayList<>(fileList.keySet());
//       Collections.sort(tifs);

       for (String key: tifs) {
       List<File> files = fileList.get(key);

          // sorter når er er behov for at listen er sorteret, ikke mens der hentes ud
          Collections.sort(files);
//          for (File tifFile: files)
//          {
//            int numTifs = tifs.size();  // 2 or many pages
        int numTifs = files.size();
        BufferedImage image[] = new BufferedImage[numTifs];
        for (int i = 0; i < numTifs; i++)
        {
            SeekableStream ss = new FileSeekableStream(tifs.get(i));
//            try (SeekableStream ss = new FileSeekableStream(tifs.get(i))) {
                //            SeekableStream ss = new FileSeekableStream(tifs[i]);
                ImageDecoder decoder = ImageCodec.createImageDecoder("tiff", ss, null);
                PlanarImage pi = new NullOpImage(decoder.decodeAsRenderedImage(0), null, null, OpImage.OP_IO_BOUND);
                image[i] = pi.getAsBufferedImage();
        }

        TIFFEncodeParam params = new TIFFEncodeParam();
        params.setCompression(TIFFEncodeParam.COMPRESSION_DEFLATE);
        System.out.println("Output: " + too);
        OutputStream out = new FileOutputStream(too + "\\" + "fff" + ".tif");
        ImageEncoder encoder = ImageCodec.createImageEncoder("tiff", out, params);
        List<BufferedImage> list = new ArrayList<BufferedImage>(image.length);
        for (int i = 1; i < image.length; i++) {
            list.add(image[i]);
        }
        params.setExtraImages(list.iterator());
        encoder.encode(image[0]);
        out.close();
          }}