Aliasing and blurring in 2-D sampled imagery

The quality of image reconstructions from discrete data suffers not only from the blurring of spatial detail caused by limitations in the spatial frequency response of electrooptical systems, but also from the aliasing generated if spatial detail has been undersampled. P. Mertz F. Grey [ Bell Syst. Tech. J.13, 464 ( 1934)] and O. H. Schade [ J. Soc. Motion Pict. Telev. Eng.56, 131 ( 1955);J. Soc. Motion Pict. Telev. Eng.58, 181 ( 1952);J. Soc. Motion Pict. Telev. Eng.61, 97 ( 1953);J. Soc. Motion Pict. Telev. Eng.64, 593 ( 1955)] have observed that reasonable spot intensity profiles and photosensor aperture shapes of equivalent size result in about equal blurring but that some profiles and shapes suppress aliasing better than others. This paper presents quantitative results of the magnitude of aliasing and blurring as a function of random radiance fields typical for natural scenes and of spatial responses and sampling intervals typical for TV cameras and optical-mechanical scanners. These results indicate that aliasing may often be a larger source of degradation than either blurring or electronic noise.