Based on high-level geometric knowledge, especially symmetry, imposed upon objects in images, we demonstrate in this paper how to edit images in terms of correct 3-D shape and relationships of the objects, without explicitly performing full 3-D reconstruction. Symmetry is proposed as the central notation that unifies both conceptually and algorithmically all types geometric regularities such as parallelism, orthoganality, and similarity. The methods are extremely simple, accurate, and easy to implement, and they demonstrate the power of applying scene knowledge.