The Code of Best Practices in Fair Use for the Visual Arts is based on a consensus of professionals in the visual arts who use copyrighted images, texts, and other materials in their creative and scholarly work and who, through discussion groups, identified best practices for using such materials.
From Stanford University, provides an introduction to the permissions process. Various sections address website permissions, academic & educational permissions, and releases. "Copyright Research" provides a very detailed look at researching copyright ownership of a work.
The Digital Image Rights Computator (DIRC) program is intended to assist the user in assessing the intellectual property status of a specific image documenting a work of art, a designed object, or a portion of the built environment.