05396559 is referenced by 179 patents and cites 8 patents.

A security device for use on identification cards, monetary documents, and the like using a reference pattern and a message pattern each having the appearance of a random pattern of dots. The reference pattern is a dense pattern of randomly positioned dots, and the message pattern is a modulated version of the reference pattern in which the dots of the reference pattern are slightly repositioned by an amount depending on the grey value or color value of a message image at each dot location. The message image is decrypted and becomes visible with a range of grey values when it is viewed through a film transparency of the reference pattern. The dot pattern may be printed, embossed or recorded as a photograph or a hologram. Decryption of the message image may be accomplished by viewing through a contact mask, superposition of images of the message pattern and reference pattern, by viewing the message pattern through a mask positioned at a real image of the reference pattern, or like means.

Title
Anticounterfeiting method and device utilizing holograms and pseudorandom dot patterns
Application Number
7/574647
Publication Number
5396559
Application Date
August 24, 1990
Publication Date
March 7, 1995
Inventor
Stephen P McGrew
149-B Josephine St., Santa Cruz, 95060
CA, US
Agent
Wells St John Roberts Gregory & Matkin
IPC
G09C 5/00
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