/usr/lib/x86_64-linux-gnu/libvigraimpex.so is in libvigraimpex-dev 1.10.0+git20160211.167be93+dfsg-5ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libvigraimpex.so.6