Retrieval of symmetrical image blur using zero sheets

The analytically continued Fourier transform of a two-dimensional image van ishes to zero on a two-dimensional surface embedded in a four-dimensional s pace. This surface uniquely characterises the image and is known as a 'zero sheet'. Since the manipulation of a function in four-dimensional space is cumbersome, the projections of zero sheets, known as 'zero tracks' are calc ulated. This knowledge of zero sheets can be extended to a number of practi cal applications including image processing. Image restoration can be reali sed without prior knowledge of the point spread function, i.e. blind deconv olution is possible even when only a single blurred image is given. If the blurred image concerned contains a point spread function with diagonal symm etry, the point zeros calculated row-wise and column-wise contain some simi larities, which supports retrieval of both the true image and a point sprea d function. This novel scheme performs the separation effectively in the ab sence of contamination.