Question about PDF manipulation

On Fri, 2005-06-03 at 15:48 +0000, Jules Richardson wrote: fount it at: http://partners.adobe.com/public/developer/pdf/index_reference.html ... via google; any variation on "PDF specification" through Adobe's own website found nothing! Image XObject streams (section 4.8.4) seem to support an optional "Metadata stream" that appeared in version 1.4 of the PDF specification; prior to that metadata could only be attached to the doc as a whole, not to individual parts. It looks like what appears in the metadata stream is fairly tightly controlled though. What's missing is any defined way of saying what the original image was, and therefore how to either convert image metadata to PDF metadata format, or do the reverse when extracting image data back out of the PDF file. In both cases that'd be dependant on what the tools decided to do; image metadata preservation is totally up to the tools and nothing in the spec says where or how it should be preserved. I suppose that makes sense as far as Adobe are concerned; they consider PDF as an end format, and that nobody would ever want to actually deconstruct one into some other format. Likewise it's really beyond their scope to say how to convert metadata when pixel images are recoded to PDF's internal representation; as a group we'd likely have to come up with a code of conduct for that if PDF's the way forward. There is reference to an XMP "Extensible Metadata Platform" doc which I'll have to try and get hold of to see what that's all about.... No wonder there's some awful PDF tools out there; I'd never realised quite how complicated a format it is! cheers Jules