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cc-metadata - [cc-metadata] Standardizing JPEG licensing

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Subject: discussion of the Creative Commons Metadata work

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  • From: "Nathan R. Yergler" <nathan AT yergler.net>
  • To: discussion of the Creative Commons Metadata work <cc-metadata AT lists.ibiblio.org>, cctools-developer AT lists.sourceforge.net
  • Subject: [cc-metadata] Standardizing JPEG licensing
  • Date: Mon, 01 Aug 2005 10:23:07 -0500

Creative Commons has long had standard methods for embedding license information in MP3 and OGG audio files. As we begin to work on a "libcc" or similar library, we probably need to discuss best practices for embedding in other common formats. The one that matters to me today is JPEG, so I wanted to outline a couple of options and get feedback or consensus.
It seems there are two obvious possiblities for embedding CC license information in JPEG files. First, EXIF contains a "copyright" tag which is intended to be populated with a statement such as "Copyright, John Smith, 20xx. All rights
reserved." Following the example of embedding a license statement in the TCOP field of ID3v2 for MP3 files, we could embed a standard statement, such as "© 1995 Example Photographer. Licensed to the public under http://creativcommons.org/licenses/by/2.0/ verify at http://example.com/licenseinfo";. Work metadata and verification information would then be stored in an external file, in this case http://example.com/licenseinfo. This approach has the advantages that EXIF manipulation is well understood and a common operation of image editting software and sites. Additionally, other tools may be able to display CC license metadata (even if they do not validate or populate) simply because they display all available EXIF data. However, the disadvantage is that it requires metadata to be stored in an external, secondary file.

The other semi-obvious choice that comes to mind is using Adobe XMP metadata (http://www.adobe.com/products/xmp/). CC already provides a specification and instructions for using XMP metadata in Adobe applications such as Photoshop (http://creativecommons.org/technology/xmp-help) and Adobe provides an SDK (http://partners.adobe.com/public/developer/xmp/sdk/index.html) for embedding XMP in several file formats. Using XMP has two primary advantages. First, it allows us to bundle metadata with the file so users have a single package to worry about. Second, it allows some standardization across file formats of available metadata. A third, less clear advantage is that it may be possible to reuse some code across file formats for interpretting the CC metadata, as I believe the SDK abstracts some of the implementation details. The disadvantages for this approach are that it requires learning or interpretting the Adobe SDK documentation, and it may be more difficult to convince third-party developers to implement a system that is seen as more difficult to implement.

So what I'd like is feedback and ideas; does anyone have experience with the XMP SDK? Anyone have strong feelings (and arguments to back them up) either way? Personally I'm sort of on the fence at this point, and can see advantages to both approaches. There's actually nothing preventing a user from implementing both, but it seems like it would be helpful to have a "standard" way of doing this to promote application interoperability.

Thanks,

Nathan R. Yergler
Software Engineer
Creative Commons





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