Hybrid optical-digital pattern recognition apparatus and method

An improved pattern recognition method comprising the steps of,

• providing a photographic transparency which stores a two dimensional image function having patterns to be classified,
• providing a beam of coherent light,
• sampling said transparency at a plurality of sampling locations with said beam of light, whereby after passing through said transparency said beam of light is modulated with information corresponding to a portion of said two dimensional image function,
• deriving first data which is indicative of the optical power spectrum of said sampled locations of said image function from said information in said beams of light,
• deriving second data which is indicative to the spatial intensity distribution of said sampled locations of said image function from the information contained in said beams of light,
• analyzing said first data indicative of said optical power spectrum to determine whether it meets predetermined criteria, and,
• if said first data meets said predetermined criteria, analyzing said second data.