[CREATE] OpenRaster minimal implementation

[Martin Renold]

hello,

I would like to finalize a minimal core of the OpenRaster specification
around January.

The reason is that I have implemented layers in MyPaint, and since there is
no plan to add all the heavy "image manipulation" features that other
programs do better anyway, the users would greatly benefit if they could
just open their images in GIMP/Krita/etc for postprocessing.

My requirements are much lower than where OpenRaster aims. I think it covers
what Cyrille has called "OpenRaster / Long-term Archiving".

I see OpenRaster mostly as an export file format; I have no ambition to
implement many new features just to be able to import all possible
OpenRaster documents. The other way around, I think the consensus is that
any MyPaint-only extensions (like per-stroke tablet event logs) should not
be stored redundantly inside those documents?

Either way, for most MyPaint users this minimal OpenRaster should be good
enough as their primary file format.

The OpenRaster specification draft in the wiki did cover all my needs (one
PNG for each layer) except for the file layout. I have specified this in the
wiki now, with a sample .ora file and a link to my (fully working) save/load
implementation:

http://create.freedesktop.org/wiki/index.php/OpenRaster

So - is this something that GIMP and Krita and other projects would be happy
to load and stay compatible with as it is, when OpenRaster is implemented?

What is missing/wrong/incomplete?
What should the mime type be?

Should it have a different filename extension to distinguish itself from
other OpenRaster formats?

bye,
Martin