  A beyond Horndeski theory is considered that admits wormholes, black holes
and naked singularities. In this theory the shadow images of the black holes
and the exotic compact objects (ECOs), illuminated by an optically and
geometrically thin disk, are investigated. The results show that the three
kinds of objects cast unlike shadow images, in particular, because the
different objects possess a different number of light rings. The different
boundaries of the accretion disk also affect the images. This may provide
further insight into the nature of the shadow images of massive compact
objects.
