@Nermander : in that case i would suggest to create a pdf and extract the images from there : - )
@AdmFubar : yes, i thought that it might be missing. but rather than fighting the xml, the better solution is to create the commands for exporting the images and submit a patch (or ask the community to create the commands). then the problem is not only solved for the one user, but for everybody (creating a command for the scripter is a bit more tedious than necessary, but to 90% copy paste work)
thought i might have a solution, and tried "collect for output" option .. alas embedded images stay firmly planted in the .sla and not exported into a sub-directory as i had hoped.
From what i can gather by looking over the available commands in python, there seems to be no option to allow exporting embedded images via a script. I checked even for a command to remove the embedding, nothing available to implement that idea.
Look like the only recourse is to parse the .sla , find the point(s) where the embedded image(s) and decode,extract and save them.