Dumping metadata with javax.imagio

[Brian S O'Neill]

Sometimes JPEG files, especially from digital cameras, have a bunch of
metadata. I'd like to read a JPEG file and write it back out, stripping
out this metadata.

The javax.imageio package provides nice methods for reading and writing
image files, but I cannot figure out a way to write the new JPEG out
without having to recompress and lose data. If the compression quality
is set to highest, does this preserve the original quality without
increasing file size?

Is there any special way to make javax.imageio support what I want, or
is there another API that can do this?

 

[Marco Schmidt]

Brian S O'Neill:

Sometimes JPEG files, especially from digital cameras, have a bunch of
metadata. I'd like to read a JPEG file and write it back out, stripping
out this metadata.

If it doesn't have to be Java try the jpegtran command line utility:

$ jpegtran -copy none input.jpg > output.jpg

The javax.imageio package provides nice methods for reading and writing
image files, but I cannot figure out a way to write the new JPEG out
without having to recompress and lose data. If the compression quality
is set to highest, does this preserve the original quality without
increasing file size?

If quality is set to highest you do lossy recompression, and you may
lose some more quality (but not much). File size will increase, though
(at least according to the test I just ran).

Is there any special way to make javax.imageio support what I want, or
is there another API that can do this?

I've listed some Java metadata libraries at
<http://www.geocities.com/marcoschmidt.geo/jpeg-image-file-format.html>.
But I don't think they can do what you ask for.

javax.imageio - I've yet to see some documentation on the metadata
part that explains (with code examples) what can be done with this
potentially powerful library. Sorry, can't help there.

Your best bet from within Java is probably running jpegtran with
Runtime.exec.

Regards,
Marco

 

[ak]

Sometimes JPEG files, especially from digital cameras, have a bunch of

metadata. I'd like to read a JPEG file and write it back out, stripping
out this metadata.

it is possible but ... why?

____________

http://reader.imagero.com the best java image reader.

 

[Brian S O'Neill]

The EXIF format used by many digital cameras supports rich metadata,
including audio samples. For a website that supports user image
submission, you might want to serve the main image, not hidden metadata.

 

[ak]

I have written such utility long time ago (and forgot about it.
It is a part of ImageroReader (http://reader.imagero.com)
see http://reader.imagero.com/doc/com/imagero/reader/jpeg/FilterAppN.html
for more info;

____________

http://reader.imagero.com the best java image reader.