Marco Amadori [ Editor ]
Jigdo requires that the image size is due to the number of debian packages available on it. Then you just download a binary diff regarding the part not composed by the debian packages, like the boot loader and it’s environment, some documents and images, tipical around 10 Mb; then jigdo merges the packages with the diff to obtain the original iso.
Live images cointains just a few packages related to debian installer or not at all if the installer is not present on the image and the great part of the image is due to the presence of a preinstalled compressed system. The diff will be equal to the whole iso, so providing a jigdo for a live system would be useless and meningless.