Images don't have to contain a full root file system and kernel, as they're constructed from packages they can contain anything in a package.
For example, if you were publishing the API documentation for your SDK online somewhere then generating a tarball of all the API docs would be a good start. This would be an image which just contained the -doc packages, and nothing else:
# Use PACKAGE_INSTALL directly to bypass the convenience layers and specify exactly what packages should be installed PACKAGE_INSTALL = "gtk+3-doc glib-2.0-doc" # Don't want any image features such as a package manager IMAGE_FEATURES = "" # Don't want any locales to be installed IMAGE_LINGUAS = "" # Just generate a tarball IMAGE_FSTYPES = "tar.gz" # Don't generate the ldconfig cache LDCONFIGDEPEND = "" # This is an image inherit image
This will create an image which just contains the packages listed in PACKAGE_INSTALL (and their dependencies), and nothing else.