I have a compressed tiff image file with six images compressed (not in multi pages) . I have offset and length of data for each image

Question

I have to read a tiff image which is compressed of 6 images and separate the images into 6 different tiff files. To identify the different images I am getting offset values like this from a xml file.

First image :data_offset :0
             data_length :7827
Second Image: data_offset :7827
              data_length :9624
Third Image:  data_offset :17451 ( i.e 7827+9624)
              data_length :5713
Fourth Image: data_offset :23164 (7827+9624+5713)
              data_length :9624

… similarly for all 6 images.

I have offset and length of individual images.How to split the original tiff file into different tiff image as per offset and length.

The code I am using below is reading the original tiff file and coping the same file.Output is the tiff file with single image.

public class TiffImageReader {

    public static void main(String[] args) throws FileNotFoundException, IOException {
        File file = new File("C://DS.tiff");
        FileInputStream fis = new FileInputStream(file);
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        byte[] buf = new byte[1024];
        try {
            for (int readNum; (readNum = fis.read(buf)) != -1; ) {
                //Writes to this byte array output stream
                bos.write(buf, 0, readNum);
                System.out.println("read " + readNum + " bytes,");
            }
        }
        catch (IOException ex) {
            Logger.getLogger(ConvertImage.class.getName()).log(Level.SEVERE, null, ex);
        }

        byte[] bytes = bos.toByteArray();
        ByteArrayInputStream bis = new ByteArrayInputStream(bytes);
        Iterator<?> readers = ImageIO.getImageReadersByFormatName("tiff");
        ImageReader reader = (ImageReader) readers.next();
        Object source = bis;
        ImageInputStream iis = ImageIO.createImageInputStream(source);
        reader.setInput(iis, true);
        ImageReadParam param = reader.getDefaultReadParam();
        Image image = reader.read(0, param);
        BufferedImage bufferedImage = new BufferedImage(image.getWidth(null), image.getHeight(null), BufferedImage.TYPE_INT_RGB);
        Graphics2D g2 = bufferedImage.createGraphics();
        g2.drawImage(image, null, null);
        File imageFile = new File("C:// DSCOPY.tiff");
        ImageIO.write(bufferedImage, "tiff", imageFile);
        System.out.println(imageFile.getPath());
    }
}

If I make byte to 1 and put on echeck at first offset 7827 and try to write the image ..Its showing ArrayOutofIndex..

"for (int readNum; (readNum = fis.read(buf)) !== 7827;)"

How to use offset and length to split my file?

Plz help.

Answer 1

Here's a modified version of you code that reads each image from your multi image TIFF file, splits it and writes each image back as single image TIFF.

Note that it assumes you have a single TIFF with 6 images as input, which is the most common case (see comment section).

public class TiffImageReader {
    public static void main(String[] args) throws IOException {
        File file = new File("C://DS.tiff");
        ImageInputStream iis = ImageIO.createImageInputStream(file);

        Iterator<ImageReader> readers = ImageIO.getImageReaders(iis);
        if (readers.hasNext()) {
            // Get TIFF reader, and set input
            ImageReader reader = readers.next();
            reader.setInput(iis);

            // Find number of images, and iterate
            int numImages = reader.getNumImages(true);
            for (int i = 0; i < numImages; i++) {
                // For each image in the file, read and write as standalone TIFF
                BufferedImage image = reader.read(i, null);
                File imageFile = new File(String.format("C://DSCOPY_%d.tiff", i));
                ImageIO.write(image, "tiff", imageFile);
                System.out.println(imageFile.getPath());
            }
        }
        else {
            System.err.printf("No image reader for %s\n", file.getPath());
        }
    }
}