qemu-img is a pretty good Rosetta stone for image formats but it is missing support some format versions. In order to bring qemu-img up-to-date with the latest disk image formats we will need to find specific image files and/or software versions that produce image files that qemu-img cannot understand today.
If you have image files that qemu-img is unable to manipulate, please respond with details of the software and version used to produce the image. If possible please include a link to a small example image file. Stefan