An optical nonsymmetrical imaging system composed of two anamorphic spectrum analyzers in cascade is implemented. This system can provide an undistorted final image in spite of the geometrical distortion effects in the intermediate Fourier plane. The introduction of chromatic sector filters in this plane provides a real-time technique to pseudocolor encode the spatial frequency information of a black-and-white transparency. In this way, greater discrimination is achieved in the angular orientation of object details that generate the same spatial frequencies. Experimental pseudocolored images, obtained with a symmetrical system and a nonsymmetrical system, of a black-and-white transparency are shown.
M. S. Millan,
"Application Of Anamorphic Systems To Directional Pseudocolor Encoding," Optical Engineering 27(2), 272129 (1 February 1988). http://dx.doi.org/10.1117/12.7976657