Comment 4 for bug 189954

nojhan (nojhan-gmail) wrote :

One can want Exif, XMP, IPTC or DC, RDF etc. The problem I see here is that none of them are standard in PNG. Thus, one cannot be sure that all softwares can read (and more important, save after edits) the metadata.

A first simple step would be to use the iTXt chunk, with standards keywords. Then, as the specs permits to add new keywords, it should be possible to support XMP or a subpart of Exif as well (as far as I comprehend the specs, but I'm not an expert).

More infos:
* Some details on the keywords: http://libpng.nigilist.ru/pub/png/spec/1.2/PNG-Chunks.html#C.Anc-text
* Some links about PNG and metadata: http://heim.ifi.uio.no/~gisle/blog/?p=3