Deblurring images is a very attractive subject in optical information processing. The content of this paper is making an arbitrary blurring of alphabets "H" by a convolution with a random array in the space domain, and then use a filter in a frequency plane to eliminate the blur by division operation. The complex space filters produced by the computer-generated hologram method can construct many new and fascinating coding and decoding systems for dilute objects. Since the application of the technique of computer-generated hologram these systems become not only more flexible and ambiguous in coding but also more effective in tJie process of decoding. In this paper several computer-generated filters inverse filter, Wiener filter and Wiener filter of exponential type have been described. The capability of all these filters for cryptology has been tested and compared experimentally.