Copyright law is designed to protect the rights of creators of artistic, literary, musical and dramatic works of all kinds from having their work exploited or misused. As such it protects their rights to charge for the work and time they have put in to their creations, and also their moral rights to control how their work is used by others.
Copyright law applies to all manner of materials and applies not just to printed publishing, but to digital publishing as well, including photographic images and digital graphic art work.