Need to extract compression used in TIFF...

Question

I would like to extract some information from a TIFF image. I would like to know the compression scheme used for each page. I don't really need to decode the TIFF image. I am specifically needing to know whether the TIFF file is using type 6 JPEG compression or type 7 JPEG-in-TIFF compression, and I need to know this information for each page (as some images seem to be "mixed").
Do I need JAI to do this? How would I do this?

Answer 1

Have you actually managed to use ImageIO to read any images yet? That's where you need to start. I'm not going to go over that now as it has been covered many times by many people.
Once you have an ImageReader object up and running, you'll need to know a little bit more about TIFF metadata. The tag number for the compression value is '259'. I don't know what values the compressions you're talking about will be, but you'll soon find out.
The following code should (hopefully) take the TIFF metadata out of the ImageReader and display what the image's compression is. The TIFF files I've been working with all have Group 4 Fax compression (the value this displays is just '4'), so I don't know how your results are going to look. Please let us know how you get on!
TIFFDirectory tiffDir = TIFFDirectory.createFromMetadata(reader.getImageMetadata(image));
TIFFField tf = tiffDir.getTIFFField(259);
TIFFTag tag = tf.getTag();
String compressionString = tf.getAsString(0);