 Hyman’s shape-principle employs the concept of an object’s occlusion shape, i.e., the 2-D cross-section of the cone of light it subtends to a viewer’s eye. (The concept is similar to Hopkins’s outline shape; see below,  §3.2.)  For example, the occlusion shape of a circular coin viewed obliquely is an ellipse. This shape, Hyman argues, is a visible property of the coin. It is especially salient when an object is backlit, and appears in silhouette. It is relative to a point of view, and changes as the point of view changes. But Hyman insists that relative does not mean subjective. An object’s occlusion shape “is not merely a feature of the viewer’s experience. It belongs to optics, not psychology” (2012: 143; cf. Peacocke 1987). Hyman’s shape-principle is that the shape of a region on a picture’s surface (or, in the case of anamorphic pictures, its occlusion shape relative to the intended point of view of a spectator) is identical to the occlusion shape of the object it represents, relative to the implicit point of view. In other words, there is an exact resemblance between these shapes (2006: 81).