Coherent Optical Processing of Motion-Degraded Images.

摘要

A technique is described whereby a photograph of a given scene,degraded by linear image motion during exposure,can be,in the absence of noise,restored to an ideal geometrical image. The technique is based upon the principles of linear systems theory. Therefore an optical imaging system is shown to be,under appropriate conditions, a linear and space-invariant system. With coherent illumination,such an optical system performs a linear mapping of complex amplitude between the object and image planes whereas,under incoherent illumination,it is a linear mapping of intensity. It is also shown that a positive lens is capable of displaying,under coherent illumination,the spatial spectrum or Fourier transform of a given two-dimensional object function. The impulse response and transfer functions associated with linear image motion are described. With the degraded photograph as the input to a coherent processing system,in which the spectrum of the input is displayed at some intermediate plane, a filter is designed which,when inserted into that plane,modifies the transfer function. As a result,the output image more closely resembles the ideal geometrical image. As a test of the theory a long narrow slit,simulating the photograph of a moving point,was used as the input to a processing system. The resulting output image was a pair of point images separated by a distance equal to the length of the slit. Thus for the particular filter used,an arbitrary smeared input function would yield an output comprising two restored images whose centers are separated by the amount of linear image motion. (Author)