How to write simple Exif metadata to JPEG from scratch.

I don’t understand how to write simple Exif metadata to a JPEG file I’ve read using Java Image I/O.

I’m successfully reading, processing, and writing JPEG metadata using Java Image I/O. It’s works fine.

I set my image reader to ignore reading metadata. I don’t care about the original metadata (in this context). Indeed the original JPEG may have already had its metadata removed, and have no metadata whatsoever:

ImageInputStream imageInputStream= …;
ImageReader imageReader = …;
ImageReadParam imageReadParam = imageReader.getDefaultReadParam();
imageReader.setInput(imageInputStream, true, true);
Buffered Image image = imageReader.read(0, imageReadParam);

I write it out:

ImageWriter imageWriter = getImageWriter(imageReader);
ImageWriteParam imageWriteParam = imageWriter.getDefaultWriteParam();
…
final ImageOutputStream imageOutputStream = …;
imageWriter.setOutput(imageOutputStream);
IIOImage iioImage = new IIOImage(newImage, null, null);
imageWriter.write(null, iioImage, imageWriteParam);

This gives me no metadata, as I would expect.

Now with TwelveMonkeys, I want to add the simplest of the very simplest Exif metadata to my JPEG. Let’s say I want to add the Exif field ImageDescription (270, 0x010E) with a value of “foobar”. What could be simpler? But I don’t see how to do that with TwelveMonkeys.

In How to write Exif to a JPEG with TwelveMonkeys’ ExifWriter class, @haraldk mentioned some sort of super low-level approach that involved actually serializing strings to bytes. I’m not sure how this relates to the TwelveMonkeys EXIFWriter/TIFFWriter, as I see that they seem to do serializing internally.

But the bigger issue is how to get an IIOMetadata instance. If I had one of those, I could just pass it to new IIOImage(newImage, null, iioMetadata) couldn’t I? I see that there is a JPEGImage10Metadata class, but how do I get one of those? Moreover how do I do this in a plugin-agnostic way, so that I don’t tie the code to TwelveMonkeys?

I’m a little lost here. Could someone point me in the right direction? Surely writing a single Exif “foobar” description value from scratch is the simplest Exif test I could make, but I can’t even figure out how to do that.

[garretwilson]

However it appears that Apache Commons Imaging can’t even write two simple Exif values to a JPEG without corrupting them!

I wanted to circle back and note that I was mistaken on this point. As I explained in IMAGING-281, the Exif property in question was a special Windows property that instead of using UTF-8 required UCS-2 to be used. That’s why a single tag seemed to “corrupted” while the others were working.

So Apache Commons Imaging is able to write metadata from scratch to a JPEG, although it requires rewriting an existing image. For now this is working for me, although it would be preferable at some point to add the metadata dynamically while I am processing it using Java Image I/O.

[haraldk]

Closing for now. Might add something to the Wiki later.