When a film or TV production shoots unit stills, the talent in those images usually have a contractual right to review and approve how they appear. Getting that right (across hundreds or thousands of frames, multiple cast members and tight publicity deadlines) is what talent image approvals are all about.
These guides explain how the process works in practice: what kill rights are, how solo and group approval percentages are typically negotiated, and the step-by-step workflow that takes a shoot from camera to a clean set of approved, deliverable stills.