A little poking and emailing comes up with interesting links. Dave Beckett has embedded RDF into a PNG by using a tEXt field called 'Metadata'. However, he doesn't have any nice tools to do this and usually uses pnmtopng (which allows the user to specify text chunks). I poked a libpng but that doesn't really allow me to fiddle with the chunks.

So I'm announcing PyPNG! A very small and rather poor Python (plus a smidge of C to do CRCs) library with grand ambitions. At the moment I can copy a PNG file (by reading the chunks, and then writing them again), display the text chunks, et la piece de resistance: a tool to set the content of an arbitary text chunk! PNGs with embedded RDF, here I come.

Once I've fiddled with the library design a little I'll write a PNG Explorer (hmm, png:/// in Nautilus is tempting) and a Metadata Editor for PNG files. Then I'll try and do exactly the same for JPEG files. Finally of course I'll have to write the web front-end.

No downloads yet, but if you want the source ask for it. Hopefully I'll have a sane tarball of PyPNG done this week though.