ABSTRACT
When a lens forms an image of an object, a continuum of points in the object contribute to form an image that itself consists of a continuum of points. For many other imaging systems (in particular many electro-optical systems) this is not the case; instead the image is built up from discrete samples of the intensity distribution in the object. These are referred to as sampled imaging systems. The important point about such systems is that in general they are not isoplanatic (i.e. they do not satisfy the condition of stationarity that requires that the shape of the point, or line, spread function does not change with position in the image) and therefore the simple form of OTF theory does not strictly describe the process of image formation for this type of system.
